Journal Description
Spectroscopy Journal
Spectroscopy Journal
is an international, peer-reviewed, open access journal on all aspects of spectroscopy published quarterly online by MDPI.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- Rapid Publication: first decisions in 18 days; acceptance to publication in 4 days (median values for MDPI journals in the second half of 2024).
- Recognition of Reviewers: APC discount vouchers, optional signed peer review, and reviewer names published annually in the journal.
- Spectroscopy Journal is a companion journal of Applied Sciences.
Latest Articles
Spectroscopic Advances in Real Time Monitoring of Pharmaceutical Bioprocesses: A Review of Vibrational and Fluorescence Techniques
Spectrosc. J. 2025, 3(2), 12; https://doi.org/10.3390/spectroscj3020012 - 1 Apr 2025
Abstract
The pharmaceutical industry has witnessed exponential growth in production volumes, driven by factors such as an aging global population and the COVID-19 pandemic. To meet the demand for high product quality alongside increased productivity, there is a growing emphasis on developing innovative Fermentation
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The pharmaceutical industry has witnessed exponential growth in production volumes, driven by factors such as an aging global population and the COVID-19 pandemic. To meet the demand for high product quality alongside increased productivity, there is a growing emphasis on developing innovative Fermentation Analytical Technology (FAT) and Process Analytical Technology (PAT) tools for real-time performance monitoring, modeling, measurement, and control. Building on our earlier work involving in-line monitoring of Bordetella pertussis fermentations using fluorescence spectroscopy, this review explores and compares the applications of vibrational and fluorescence spectroscopy for real-time bioprocess monitoring. We examine recent technological advancements and ongoing challenges in the field. Various spectroscopic techniques are evaluated in terms of cost-effectiveness and practical applicability, with a particular focus on in-line spectroscopy as a promising, low-cost solution for effective bioprocess monitoring.
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(This article belongs to the Special Issue Feature Papers in Spectroscopy Journal)
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Open AccessArticle
The Presence of Excitons in Short Single-Stranded DNA Revealed by Absorption and Circular Dichroism Spectroscopy
by
Alessandra Picchiotti, Amy L. Stevens, Valentyn I. Prokhorenko and R. J. Dwayne Miller
Spectrosc. J. 2025, 3(2), 11; https://doi.org/10.3390/spectroscj3020011 - 28 Mar 2025
Abstract
This paper presents a systematic absorption and circular dichroism spectroscopy study of short single strands of DNA, from 2 to 20 bases. They are composed of a sequence-specific nucleobase composition, either adenine (A), thymine (T), or AT repeats. The absorption spectra hypochromism and
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This paper presents a systematic absorption and circular dichroism spectroscopy study of short single strands of DNA, from 2 to 20 bases. They are composed of a sequence-specific nucleobase composition, either adenine (A), thymine (T), or AT repeats. The absorption spectra hypochromism and the circular dichroism one show butterfly-shaped spectra. Data analysis conducted on the spectra of these oligomers provides evidence for the formation of excitons and their delocalization length along the strand of DNA in relation to how many bases are involved in the excitonic coupling. In particular, the extent of this coupling is limited to adjacent nucleobases in the case of pure adenine strands but spans multiple nucleobases in the case of pure thymine strands. Predictably, AT repeats show a mixed behavior between the two.
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Open AccessReview
Advantages of In Situ Mössbauer Spectroscopy in Catalyst Studies with Precaution in Interpretation of Measurements
by
Károly Lázár
Spectrosc. J. 2025, 3(1), 10; https://doi.org/10.3390/spectroscj3010010 - 17 Mar 2025
Abstract
Mössbauer spectroscopy can be advantageous for studying catalysts. In particular, its use in in situ studies can provide unique access to structural features. However, special attention must be paid to the interpretation of data, since in most studies, the samples are not perfectly
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Mössbauer spectroscopy can be advantageous for studying catalysts. In particular, its use in in situ studies can provide unique access to structural features. However, special attention must be paid to the interpretation of data, since in most studies, the samples are not perfectly homogeneous. Balance and compromise should be found between the refinement of evaluations by extracting and interpreting data from spectra, while also considering the presence of possible inhomogeneities in samples. In this review, examples of studies on two types of catalysts are presented, from which, despite possible inhomogeneities, clear statements can be derived. The first example pertains to selected iron-containing microporous zeolites (with 57Fe Mössbauer spectroscopy), from which unique information is collected on the coordination of iron ions. The second example is related to studies on supported PtSn alloy particles (with 119Sn probe nuclei), from which reversible modifications of the tin component due to interactions with the reaction partners are revealed.
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Open AccessReview
The Triangle: Carotenoids–Retinoids–Cytochromes Govern Essential Functions for Development and Progression of Cancer
by
Halina Abramczyk, Monika Kopeć and Jakub Surmacki
Spectrosc. J. 2025, 3(1), 9; https://doi.org/10.3390/spectroscj3010009 - 7 Mar 2025
Abstract
In this review, we demonstrate that the carotenoids–retinoids–cytochromes c triangle is an important cancer factor controlling most aspects of the development, proliferation, and progression of cancer. Cancer is a multidimensional disease that needs a balance between the enzymes controlling the amount of carotenoids,
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In this review, we demonstrate that the carotenoids–retinoids–cytochromes c triangle is an important cancer factor controlling most aspects of the development, proliferation, and progression of cancer. Cancer is a multidimensional disease that needs a balance between the enzymes controlling the amount of carotenoids, the production of retinoids (particularly retinoic acid), and the concentration of cytochromes (particularly cytochrome c). The proper balance between these enzymes will help in overcoming the bottleneck in cancer therapeutics using drugs. First, we discuss the impact of carotenoids on cancer. In the next section, we show how carotenoid cleavage products, including retinal, retinol, and retinoic acid, induce positive and negative effects on cancer development. Then, we discuss the impact of cytochrome c on cancer. We have demonstrated that an alteration in the cellular redox status of cytochrome c is a crucial factor in cancer, influencing numerous aspects of malignant progression. The results obtained by Raman imaging showed significant differences between normal and cancerous human cells. First, a significant redox imbalance in the hem group of cytochrome c with the upregulation of the reduced form of hem is observed. Cancer tissue has a higher concentration of reduced cytochrome c than normal tissue. Secondly, both breast and brain tumors exhibit enhanced de novo lipogenesis in comparison to normal cells. Third, this research illustrates the essential function of the extracellular matrix in oxidative phosphorylation and apoptosis pathways.
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(This article belongs to the Special Issue Vibrational Spectroscopy and Biospectroscopy: Commemorative Issue Saluting the Pioneering Contributions of Prof. Henry Mantsch)
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Open AccessArticle
Towards Fast Quantum Cascade Laser Spectrometers for High-Throughput and Cost-Effective Disease Surveillance
by
Mauro Pazmiño-Betancourth, Aleksandr Boldin, Victor Ochoa-Gutierrez, Richard A. Hogg, Francesco Baldini, Mario González-Jiménez, Klaas Wynne and David Childs
Spectrosc. J. 2025, 3(1), 8; https://doi.org/10.3390/spectroscj3010008 - 7 Mar 2025
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Fourier transform infrared (FTIR) spectroscopy, coupled with machine learning (ML) analysis can be used for disease monitoring with high speed and accuracy, including the classification of mosquito samples by species, age and malaria detection. However, current FTIR instruments use low-brightness thermal light sources
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Fourier transform infrared (FTIR) spectroscopy, coupled with machine learning (ML) analysis can be used for disease monitoring with high speed and accuracy, including the classification of mosquito samples by species, age and malaria detection. However, current FTIR instruments use low-brightness thermal light sources to generate infrared light, which limits their ability to measure complex biological samples, especially where high spatial resolution is necessary, such as for specific mosquito tissues. Moreover, these systems lack portability, which is essential for field applications. To overcome these issues, spectrometers using quantum cascade lasers (QCLs) have become an attractive alternative for building fast, and portable systems due to their high electrical-to-optical efficiency, small size, and potential for low-cost. Here, we present a QCL-based spectrometer prototype designed for large scale, low-cost, environmental field-based disease surveillance.
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Open AccessArticle
A Combined Raman Spectroscopy and Chemometrics Study of the Interaction of Water-Soluble Polymers with Microorganisms
by
Thomas J. Tewes, Arjana Kaba, Felix H. Schacher and Dirk P. Bockmühl
Spectrosc. J. 2025, 3(1), 7; https://doi.org/10.3390/spectroscj3010007 - 22 Feb 2025
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Optical spectroscopic methods such as Raman spectroscopy offer several advantages for the analysis of water-soluble polymers (WSPs). There is often no need for complex sample preparation, and measurements are usually rapid, mostly non-destructive and no harmful chemicals are required. In this work, we
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Optical spectroscopic methods such as Raman spectroscopy offer several advantages for the analysis of water-soluble polymers (WSPs). There is often no need for complex sample preparation, and measurements are usually rapid, mostly non-destructive and no harmful chemicals are required. In this work, we investigated WSPs and their interaction with bacteria using Raman spectroscopic methods. We analyzed four different WSPs, each with three different molar masses, in solid form using Raman microscopy, and in aqueous solutions using another Raman system designed for measurements in cuvettes, to train predictive models for concentration determination. Thus, we were able to show both the high potential of these approaches, especially for fast and easy investigations both qualitatively and quantitatively, as well as their limitations. Furthermore, we chose one of the molar masses of each tested polymer to carry out extensive Raman spectroscopic investigations with Escherichia coli and Enterococcus faecium, and revealed that bacterial cells exposed to polymers exhibited distinguishable spectral characteristics compared to those not in contact with polymers. Using Raman microscopy combined with partial least squares discriminant analysis (PLS-DA), we effectively distinguished between these groups. Further chemometric analysis indicated potential polymer-induced modifications to the bacterial cell membranes. While this differentiation may partly reflect polymer interactions at the membrane level, it could also correspond to shifts in bacterial growth phases. Together, these findings suggest a complex interplay between polymer exposure and bacterial physiological states.
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Open AccessArticle
Point-of-Care No-Specimen Diagnostic Platform Using Machine Learning and Raman Spectroscopy: Proof-of-Concept Studies for Both COVID-19 and Blood Glucose
by
Allen B. Chefitz, Rohit Singh, Thomas Birch, Yongwu Yang, Arib Hussain and Gabriella Chefitz
Spectrosc. J. 2025, 3(1), 6; https://doi.org/10.3390/spectroscj3010006 - 19 Feb 2025
Abstract
Significance: We describe a novel, specimen-free diagnostic platform that can immediately detect both a metabolite (glucose) or an infection (COVID-19) by non-invasively using Raman spectroscopy and machine learning. Aim: Current diagnostic testing for infections and glucose monitoring requires specimens, disease-specific reagents and processing,
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Significance: We describe a novel, specimen-free diagnostic platform that can immediately detect both a metabolite (glucose) or an infection (COVID-19) by non-invasively using Raman spectroscopy and machine learning. Aim: Current diagnostic testing for infections and glucose monitoring requires specimens, disease-specific reagents and processing, and it increases environmental waste. We propose a new hardware–software paradigm by designing and constructing a finger-scanning hardware device to acquire Raman spectroscopy readouts which, by varying the machine learning algorithm to interpret the data, allows for diverse diagnoses. Approach: A total of 455 patients were enrolled prospectively in the COVID-19 study; 148 tested positive and 307 tested negative through nasal PCR testing conducted concurrently with testing using our viral detector. The tests were performed on both outpatients (N = 382) and inpatients (N = 73) at Holy Name Medical Center in Teaneck, NJ, between June 2021 and August 2022. Patients’ fingers were scanned using an 830 nm Raman System and then, using machine learning, processed to provide an immediate result. In a separate study between April 2023 and August 2023, measurements using the same device and scanning a finger were used to detect blood glucose levels. Using a Dexcom sensor and an Accu-Chek device as references, a cross-validation-based regression of 205 observations of blood glucose was performed with a machine learning algorithm. Results: In a five-fold cross-validation analysis (including asymptomatic patients), a machine learning classifier using the Raman spectra as input achieved a specificity for COVID-19 of 0.837 at a sensitivity of 0.80 and an area under receiver operating curve (AUROC) of 0.896. However, when the data were split by time, with training data consisting of observations before 1 July 2022 and test data consisting of observations after it, the model achieved an AUROC of 0.67, with 0.863 sensitivity at a specificity of 0.517. This decrease in AUROC may be due to substantial domain shift as the virus evolves. A similar five-fold cross-validation analysis of Raman glucose detection produces an area under precision–recall curve (AUPR) of 0.58. Conclusions: The combination of Raman spectroscopy, AI/ML, and our patient interface admitting only a patient’s finger and using no specimen offers unprecedented flexibility in introducing new diagnostic tests or adapting existing ones. As the ML algorithm can be iteratively re-trained with new data and the software deployed to field devices remotely, it promises to be a valuable tool for detecting rapidly emerging infectious outbreaks and disease-specific biomarkers, such as glucose.
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Open AccessArticle
Effect of Dehydration on Light-Adapted States of Bacterial Reaction Centers Studied by Time-Resolved Rapid-Scan FTIR Difference Spectroscopy
by
Alberto Mezzetti, Marco Malferrari, Francesco Francia and Giovanni Venturoli
Spectrosc. J. 2025, 3(1), 5; https://doi.org/10.3390/spectroscj3010005 - 1 Feb 2025
Abstract
Dehydration is known to affect the rate of electron transfer backreaction from the light-induced charge separation state P+QA− to the neutral ground state PQA in photosynthetic bacterial Reaction Centers. On the other hand, a 20 s continuous illumination
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Dehydration is known to affect the rate of electron transfer backreaction from the light-induced charge separation state P+QA− to the neutral ground state PQA in photosynthetic bacterial Reaction Centers. On the other hand, a 20 s continuous illumination period has been demonstrated to induce (at 297 K) formation of one or more light-adapted states at different levels of dehydration; these light-adapted states are believed to be related to peculiar response(s) from the protein. In this work, we applied time-resolved rapid-scan FTIR difference spectroscopy to investigate the protein response under dehydrated conditions (RH = 11%) at 281 K both after a flash and under prolonged continuous illumination. Time-resolved FTIR difference spectra recorded after a laser flash show a protein recovery almost synchronous to the electron transfer backreaction P+QA− → PQA. Time-resolved FTIR difference spectra recorded after 20.5 s of continuous illumination (RH = 11%, T = 281 K) surprisingly show almost the same kinetics of electron transfer back reaction compared to spectra recorded after a laser flash. This means that the mechanism of formation of a light-adapted stabilized state is less effective compared to the same hydration level at 297 K and to the RH = 76% hydration level (both at 281 K and 297 K). Time-resolved FTIR difference spectra after continuous illumination also suggest that the 1666 cm−1 protein backbone band decays faster than marker bands for the electron transfer back reaction P+QA− → PQA. Finally, FTIR double-difference spectra (FTIR difference spectrum recorded after 18.4 s illumination minus flash-induced FTIR difference spectrum) suggest that at RH = 11%, a light-adapted state different from the one observed at RH = 76% is formed. A possible interpretation is that at RH = 11%, the protein response is modified by the fact that only protons can move easily, differently from water molecules, as instead observed for RH = 76%. This probably makes the formation of a real light-adapted P+QA− stabilized state at RH = 11% unfeasible.
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(This article belongs to the Special Issue Vibrational Spectroscopy and Biospectroscopy: Commemorative Issue Saluting the Pioneering Contributions of Prof. Henry Mantsch)
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Open AccessArticle
Geometry Change of 1,3-Dicyanobenzene upon Electronic Excitation from a Franck–Condon Fit of Several Fluorescence Emission Spectra
by
Jascha Martini, Simran Amar and Michael Schmitt
Spectrosc. J. 2025, 3(1), 4; https://doi.org/10.3390/spectroscj3010004 - 21 Jan 2025
Abstract
The change in the geometry of 1,3-dicyanobenzene upon electronic excitation to the lowest excited singlet state has been elucidated by simultaneous Franck–Condon (FC) fits of the fluorescence emission spectra originating from the vibrationless origin and from four vibronic bands. The geometry changes obtained
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The change in the geometry of 1,3-dicyanobenzene upon electronic excitation to the lowest excited singlet state has been elucidated by simultaneous Franck–Condon (FC) fits of the fluorescence emission spectra originating from the vibrationless origin and from four vibronic bands. The geometry changes obtained from the FC fits were compared to the results of ab initio calculations at the SCS-CC2/cc-pVTZ level of theory. We found close agreement between the spectral determination and the theoretical prediction of the geometry changes upon excitation. The aromatic ring opens upon excitation, resulting in a symmetrically distorted structure in the excited state.
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(This article belongs to the Special Issue Vibrational Spectroscopy and Biospectroscopy: Commemorative Issue Saluting the Pioneering Contributions of Prof. Henry Mantsch)
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Open AccessArticle
Optical Gain in Eu-Doped Hybrid Nanocrystals Embedded SiO2-HfO2-ZnO Ternary Glass-Ceramic Waveguides
by
Subhabrata Ghosh, Sylvia Turrell, Maurizio Ferrari and Shivakiran Bhaktha B. N.
Spectrosc. J. 2025, 3(1), 3; https://doi.org/10.3390/spectroscj3010003 - 18 Jan 2025
Abstract
Rare-earth doped transparent glass-ceramic waveguides are playing a very crucial role in integrated optics. We fabricated ZnO-HfO2 hybrid nanocrystals embedded with 70 SiO2–(30-x) HfO2–x ZnO (x = 0, 2, 5 and 7 mol %) ternary transparent glass-ceramic waveguides
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Rare-earth doped transparent glass-ceramic waveguides are playing a very crucial role in integrated optics. We fabricated ZnO-HfO2 hybrid nanocrystals embedded with 70 SiO2–(30-x) HfO2–x ZnO (x = 0, 2, 5 and 7 mol %) ternary transparent glass-ceramic waveguides doped with 1 mol % Eu-ions. The formation and size of the nanocrystals evolved with an increase in ZnO concentration in the glass-ceramic waveguides. In this context, key factors of such nanocrystals embedded active glass-ceramic waveguides were optical losses and transparency. A lab-built m-line experimental set-up was used for the characterization of the waveguides. On the other hand, optical gain measurements of the Eu-doped hybrid nanocrystals embedded glass-ceramic waveguides were performed using the variable stripe length method. The optical amplification of the waveguides was investigated on the red emission line (5D0 → 7F2) of Eu-ions pumped by a 532 nm laser in a stripe-like geometry generated by a cylindrical lens. Here, we report, the optical gain in rare-earth activated glass-ceramic waveguides with nanocrystals of varying sizes formed in the waveguides with increasing ZnO concentration.
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(This article belongs to the Special Issue Vibrational Spectroscopy and Biospectroscopy: Commemorative Issue Saluting the Pioneering Contributions of Prof. Henry Mantsch)
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Open AccessBrief Report
Integral UV Spectrophotometric Methods for Determination of Clopidogrel Bisulphate and Metamizole Sodium in Rinse Waters from Industrial Equipment
by
Pavel Anatolyevich Nikolaychuk
Spectrosc. J. 2025, 3(1), 2; https://doi.org/10.3390/spectroscj3010002 - 16 Jan 2025
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In this paper, methods for the determination of clopidogrel bisulphate and metamizole sodium in rinse waters from industrial equipment, using multiwavelength UV spectrometry and the calculation of areas under curves, are proposed. Spectra were recorded in an aqueous medium without preliminary pH adjustment.
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In this paper, methods for the determination of clopidogrel bisulphate and metamizole sodium in rinse waters from industrial equipment, using multiwavelength UV spectrometry and the calculation of areas under curves, are proposed. Spectra were recorded in an aqueous medium without preliminary pH adjustment. A numerical integration of the spectra was performed in the wavelength range of 210 to 290 nm for clopidogrel bisulphate, and 220 to 320 nm for metamizole sodium. The methods enable the determination of clopidogrel bisulphate and metamizole sodium in solution in the concentration range of 1–100 mg/L, do not require lengthy sample preparation and complex analytical equipment, and are suitable for the routine determination of these drugs in rinse waters from industrial equipment.
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Open AccessArticle
Development of Interface-Specific Two-Dimensional Vibrational–Electronic (i2D-VE) Spectroscopy for Vibronic Couplings at Interfaces
by
Yuqin Qian, Zhi-Chao Huang-Fu, Jesse B. Brown and Yi Rao
Spectrosc. J. 2025, 3(1), 1; https://doi.org/10.3390/spectroscj3010001 - 3 Jan 2025
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Bulk 2D electronic–vibrational (2D-EV) and 2D vibrational–electronic spectroscopies (2D-VE) were previously developed to correlate the electronic and vibrational degrees of freedom simultaneously, which allow for the study of couplings between electronic and vibrational transitions in photo-chemical systems. Such bulk-dominated methods have been used
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Bulk 2D electronic–vibrational (2D-EV) and 2D vibrational–electronic spectroscopies (2D-VE) were previously developed to correlate the electronic and vibrational degrees of freedom simultaneously, which allow for the study of couplings between electronic and vibrational transitions in photo-chemical systems. Such bulk-dominated methods have been used to extensively study molecular systems, providing unique information such as coherence sensitivity, molecular configurations, enhanced resolution, and correlated states and their dynamics. However, the analogy of interfacial 2D spectroscopy has fallen behind. Our recent work presented interface-specific 2D-EV spectroscopy (i2D-EV). In this work, we develop interface-specific two-dimensional vibrational–electronic spectroscopy (i2D-VE). The fourth-order spectroscopy is based on a Mach–Zehnder IR interferometer that accurately controls the time delay of an IR pump pulse pair for vibrational transitions, followed by broadband interface second-harmonic generation to probe electronic transitions. We demonstrate step-by-step how a fourth-order i2D-VE spectrum of AP3 molecules at the air/water interface was collected and analyzed. The line shape and signatures of i2D-VE peaks reveal solvent correlations and the spectral nature of vibronic couplings. Together, i2D-VE and i2D-EV spectroscopy provide coupling of different behaviors of the vibrational ground state or excited states with electronic states of molecules at interfaces and surfaces. The methodology presented here could also probe dynamic couplings of electronic and vibrational motions at interfaces and surfaces, extending the usefulness of the rich data that are obtained.
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Open AccessArticle
Evaluation of Spatial Distribution of Crystallinity Induced by Local Heating Using Low-Frequency Raman Spectroscopy on Polyether Ether Ketone (PEEK)
by
Tomoko Numata, Naomoto Ishikawa, Toshihiro Shimada, Keith C. Gordon and Makoto Yamaguchi
Spectrosc. J. 2024, 2(4), 341-348; https://doi.org/10.3390/spectroscj2040021 - 18 Dec 2024
Abstract
Local heating was performed on a thermoplastic polymer film by contact with the tip of a soldering iron heated above the glass-transition temperature. The locally heated area was measured using microscopic Raman scattering spectroscopy, and the spatial distribution of the crystallinity was obtained
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Local heating was performed on a thermoplastic polymer film by contact with the tip of a soldering iron heated above the glass-transition temperature. The locally heated area was measured using microscopic Raman scattering spectroscopy, and the spatial distribution of the crystallinity was obtained from the low-frequency peak. The crystallinity distribution can be evaluated using the microscale spatial resolution. The temperature distribution around the locally heated area was calculated by applying the heat conduction equation, and good correspondence was obtained with the obtained crystallinity.
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Open AccessArticle
Raman Spectroscopy of Common Fertilizers in Aqueous Solution and Their Detection
by
Laurel ONeill, Maxwell Weatherington and Tim Kane
Spectrosc. J. 2024, 2(4), 332-340; https://doi.org/10.3390/spectroscj2040020 - 17 Dec 2024
Cited by 1
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Industrial agriculture, while necessary to meet current food production needs, can have damaging effects on the environment and local water supply. For monitoring purposes, Raman spectra of common fertilizers in solution are measured and presented. Raman spectra of the fertilizer species combined with
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Industrial agriculture, while necessary to meet current food production needs, can have damaging effects on the environment and local water supply. For monitoring purposes, Raman spectra of common fertilizers in solution are measured and presented. Raman spectra of the fertilizer species combined with data from Inductively Coupled Plasma Emission Spectrometry (ICP-AES) is used to construct an empirical model of contaminant concentration. This work expands upon the authors’ prior work in Raman Spectroscopy of Common Fertilizers in Bulk and in Aqueous Solution, which was presented during the virtual sessions at OSA Optical Sensors and Sensing Congress in 2021 (AIS, FTS, HISE, SENSORS, ES).
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Open AccessArticle
Laminated Information Encryption with Printer Using Laser-Induced Breakdown Spectroscopy
by
Xiang Han, Li Shen, Lixing Yao and Yu Liu
Spectrosc. J. 2024, 2(4), 322-331; https://doi.org/10.3390/spectroscj2040019 - 8 Dec 2024
Abstract
In order to improve the security of information encryption, this paper proposes a novel method based on laser-induced breakdown spectroscopy (LIBS) technology in conjunction with a commercial general-purpose inkjet printer. A “sandwich” model, comprising three layers of a black ink block, a blue
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In order to improve the security of information encryption, this paper proposes a novel method based on laser-induced breakdown spectroscopy (LIBS) technology in conjunction with a commercial general-purpose inkjet printer. A “sandwich” model, comprising three layers of a black ink block, a blue ink layer containing encrypted information, and another black ink block in order to render the information layer undetectable by other conventional optical imagers, was proposed. Because of the lower resolution requirements and better error tolerance of the Quick Response (QR) code, it was used as encryption information carrier. The “sandwich” structure was printed onto original paper using a commercial inkjet printer. The spatial distribution of the “LIBS secret key” on the paper was analyzed by LIBS spectra at different locations. After baseline removal, normalization, and spectral superposition, the contrast of decrypted images is enhanced to extract hidden information effectively. This method has the advantages of high security, low cost, and simple fabrication. It provides a new method with a potential application prospect for LIBS in the field of information encryption.
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Open AccessArticle
Vibrational Markers of a Model Circulating Metastatic Cells LLC-R9
by
Olena Gnatyuk, Denys Kolesnyk, Taras Voitsitskyi, Sergiy Karakhim, Andriy Nikolenko, Andrej Dementjev, Galina Solyanik and Galyna Dovbeshko
Spectrosc. J. 2024, 2(4), 306-321; https://doi.org/10.3390/spectroscj2040018 - 26 Nov 2024
Abstract
Metastasis in oncological diseases remains one of the main reasons for negative prognosis regarding treatment. Any new data on the biophysical and biochemical characteristics of circulating metastatic cells will help to develop a concept for antimetastatic therapy. In this study, we found a
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Metastasis in oncological diseases remains one of the main reasons for negative prognosis regarding treatment. Any new data on the biophysical and biochemical characteristics of circulating metastatic cells will help to develop a concept for antimetastatic therapy. In this study, we found a number of differences in the spectroscopic and morphological features of circulating metastatic cells. FT-IR and Raman spectra cultivated by adhesive and de-adhesive methods (with the latter used as a model for metastatic cells) have shown spectroscopic features, namely in FT-IR spectra in the region of CH stretching vibrations, which are associated with structural rearrangements in the cell membrane, as well as changes in the intensity and position of the PO2− group vibration bands correlated with proliferative activity. The spectral features in the regions of OH stretching and Amide I vibrations as well as other spectral markers of the metastatic cells grown under different cultivation conditions were derived. Raman spectra showed a redistribution of the amino acid Tyr/Trp (tryptophan to tyrosine) ratio and in Tyr doublet intensity in the region of 500–900 cm−1, as well as varying glycogen levels in different cells. The spectroscopic markers are in accordance with biochemical data. CARS and confocal optical microscopy were applied to determine the state of the cells and the F-actin expression level, which turned out to be higher for adhesive cells in comparison with de-adhesive cells. The shape and the morphological properties of the cells differ drastically. The correlation of vibrational markers with biochemical data and the cytofluorometric method was discussed.
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(This article belongs to the Special Issue Vibrational Spectroscopy and Biospectroscopy: Commemorative Issue Saluting the Pioneering Contributions of Prof. Henry Mantsch)
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Open AccessArticle
Diode Laser Absorption Spectroscopy and DSMC Calculations for the Determination of Species-Specific Diffusion Coefficients of a CO2-N2O Gas Mixture in the Transition Gas Regime
by
Kannan Munusamy, Harald Kleine and Sean O’Byrne
Spectrosc. J. 2024, 2(4), 287-305; https://doi.org/10.3390/spectroscj2040017 - 25 Nov 2024
Abstract
Multicomponent gas mixture diffusion in a microscale confined flow in the transition gas regime at Knudsen numbers (Kn) above 0.1 has potential engineering applications in gas-phase microfluidics. Although the calculation of the diffusion coefficient accounts for the influence of the concentration of other
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Multicomponent gas mixture diffusion in a microscale confined flow in the transition gas regime at Knudsen numbers (Kn) above 0.1 has potential engineering applications in gas-phase microfluidics. Although the calculation of the diffusion coefficient accounts for the influence of the concentration of other species in a multicomponent gas mixture, the higher rate of gas-wall collision at 0.1 < Kn ≤ 10 introduces additional complications not predicted by conventional calculation methods. Thus, simultaneous measurement of diffusion coefficients for multiple gas species ensures accurate estimation of the diffusion coefficient of a particular species that includes the effect of interactions with other species and wall surface conditions in a multicomponent gas mixture at Kn > 0.1. However, most experimental methods for measuring the diffusion coefficient are not species-specific and therefore cannot directly differentiate between the species diffusing in a gas mixture. Thus, this paper demonstrates a new experiment methodology consisting of a two-bulb diffusion configuration accompanied by a tunable diode laser absorption spectroscopy detection technique for species-specific, in-situ, simultaneous measurement of the effective diffusion coefficient for a CO2-N2O gas mixture in the transition gas regime. The experimental results are compared against direct simulation Monte Carlo calculations and the Bosanquet approximation showing a deviation that has not been reported in the literature before.
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Open AccessArticle
Probing the Charge State and the Intermolecular Environment by Vibrational Spectroscopy: The Peculiar Modulation of Frequencies and Band Intensities of F4TCNQ and Its Anion
by
Carlo Saporiti, Luigi Brambilla, Matteo Tommasini, Mirella Del Zoppo, Chiara Castiglioni and Giuseppe Zerbi
Spectrosc. J. 2024, 2(4), 264-286; https://doi.org/10.3390/spectroscj2040016 - 15 Nov 2024
Cited by 1
Abstract
2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) is a molecule widely employed as a very effective p-dopant of semi-conducting polymers, such as poly(3-hexylthiophene-2,5-diyl) (P3HT). The CN stretching transitions of F4TCNQ are exceptionally sensitive to the charge state of the molecule, thus allowing the doping diagnosis via IR spectroscopy.
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2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) is a molecule widely employed as a very effective p-dopant of semi-conducting polymers, such as poly(3-hexylthiophene-2,5-diyl) (P3HT). The CN stretching transitions of F4TCNQ are exceptionally sensitive to the charge state of the molecule, thus allowing the doping diagnosis via IR spectroscopy. Less pronounced frequency shifts can reveal characteristics of the intermolecular environment. We present a systematic study based on Density Functional Theory (DFT) calculations and on experiments aimed at exploring how different factors, such as the charge state and the environment, modify the vibrational spectra of F4TCNQ. While several effects on the vibrational frequencies are well known and have been thoroughly investigated in the past, this study focuses on the infrared intensities of the CN stretching modes and reveals that they are strongly affected both by the charge state of the molecule and by the surrounding medium: it is then mandatory to consider such remarkable intensity modulation for any quantitative diagnosis based on spectroscopic measurements, e.g., concerning the number of F4TCNQ molecules involved in the formation of charge transfer complexes.
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(This article belongs to the Special Issue Vibrational Spectroscopy and Biospectroscopy: Commemorative Issue Saluting the Pioneering Contributions of Prof. Henry Mantsch)
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Open AccessReview
Illuminating Malaria: Spectroscopy’s Vital Role in Diagnosis and Research
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Bayden R. Wood, John A. Adegoke, Thulya Chakkumpulakkal Puthan Veettil, Ankit Dodla, Keith Dias, Neha Mehlawat, Callum Gassner, Victoria Stock, Sarika Joshi, Magdalena Giergiel, Diana E. Bedolla and Philip Heraud
Spectrosc. J. 2024, 2(4), 216-263; https://doi.org/10.3390/spectroscj2040015 - 15 Nov 2024
Abstract
Spectroscopic techniques have emerged as crucial tools in the field of malaria research, offering immense potential for improved diagnosis and enhanced understanding of the disease. This review article pays tribute to the pioneering contributions of Professor Henry Mantsch in the realm of clinical
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Spectroscopic techniques have emerged as crucial tools in the field of malaria research, offering immense potential for improved diagnosis and enhanced understanding of the disease. This review article pays tribute to the pioneering contributions of Professor Henry Mantsch in the realm of clinical biospectroscopy, by comprehensively exploring the diverse applications of spectroscopic methods in malaria research. From the identification of reliable biomarkers to the development of innovative diagnostic approaches, spectroscopic techniques spanning the ultraviolet to far-infrared regions have played a pivotal role in advancing our knowledge of malaria. This review will highlight the multifaceted ways in which spectroscopy has contributed to the field, with a particular emphasis on its impact on diagnostic advancements and drug research. By leveraging the minimally invasive and highly accurate nature of spectroscopic techniques, researchers have made significant strides in improving the detection and monitoring of malaria parasites. These advancements hold the promise of enhancing patient outcomes and aiding in the global efforts towards the eradication of this devastating disease.
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(This article belongs to the Special Issue Vibrational Spectroscopy and Biospectroscopy: Commemorative Issue Saluting the Pioneering Contributions of Prof. Henry Mantsch)
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Open AccessArticle
Benchtop 19F Nuclear Magnetic Resonance (NMR) Spectroscopy-Optimized Knorr Pyrazole Synthesis of Celecoxib and Mavacoxib, 3-(Trifluoromethyl) Pyrazolyl Benzenesulfonamides, Non-Steroidal Anti-Inflammatory Drugs (NSAIDs)
by
Andrew Chyu, Selina Xi, Joshua Kim, Galen Liu, Indalina Chan, Seoyeon Hong, Allen Ke, Thomas Lavery, Anushree Marimuthu, Arjun Akula and Edward Njoo
Spectrosc. J. 2024, 2(4), 206-215; https://doi.org/10.3390/spectroscj2040014 - 11 Nov 2024
Abstract
Fluorinated organic compounds have demonstrated remarkable utility in medicinal chemistry due to their enhanced metabolic stability and potent therapeutic efficacy. Several examples exist of fluorinated non-steroidal anti-inflammatory drugs (NSAIDs), including diflunisal, flurbiprofen, and trifluoromethylated pyrazoles celecoxib and mavacoxib. These trifluoromethylated pyrazoles, which are
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Fluorinated organic compounds have demonstrated remarkable utility in medicinal chemistry due to their enhanced metabolic stability and potent therapeutic efficacy. Several examples exist of fluorinated non-steroidal anti-inflammatory drugs (NSAIDs), including diflunisal, flurbiprofen, and trifluoromethylated pyrazoles celecoxib and mavacoxib. These trifluoromethylated pyrazoles, which are most commonly constructed through the cyclocondensation of a trifluorinated 1,3-dicarbonyl and an aryl hydrazine, are also found in numerous other drug candidates. Here, we interrogate the effects of solvents and the presence of Brønsted or Lewis acid catalysts on catalyzing this process. We highlight the utility of benchtop 19F NMR spectroscopy in enabling the real-time quantification of reaction progress and the identification of fluorinated species present in crude reaction mixtures without the need for cost-prohibitive deuterated solvents. Ultimately, we find that the reaction solvent has the greatest impact on the rate and product yield, and also found that the relationship between the keto-enol equilibrium of the dicarbonyl starting material pyrazole formation rate is highly solvent-dependent. More broadly, we describe the optimization of the yield and kinetics of trifluoromethylpyrazole formation in the synthesis of celecoxib and mavacoxib, which is made possible through high-throughput reaction screening on benchtop NMR.
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(This article belongs to the Special Issue Feature Papers in Spectroscopy Journal)
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