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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 16 days; acceptance to publication in 5.8 days (median values for MDPI journals in the second half of 2023).
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.

Imprint Information Journal Flyer Open Access ISSN: 2813-446X

Latest Articles

15 pages, 3831 KiB

Open AccessArticle

Raman Spectra of Blood Serum as Holistic Biomarker for Differential Auxiliary Diagnoses of Attention Deficit and Hyperactivity Disorder (ADHD) in Adults

by Gizem Yavuz Dogan, Gokhan Halimoglu, Dilara Kaplanoglu, Umut Mert Aksoy, Ali Kandeger, Elif Yavuz, Sehban Kartal, Rui Fausto and Gulce Ogruc Ildiz

Spectrosc. J. 2024, 2(2), 53-67; https://doi.org/10.3390/spectroscj2020004 - 14 Apr 2024

Attention deficit and hyperactivity disorder (ADHD) is a prevalent neurodevelopmental condition, impacting approximately 10% of children globally. A significant proportion, around 30–50%, of those diagnosed during childhood continue to manifest ADHD symptoms into adulthood, with 2–5% of adults experiencing the condition. The existing [...] Read more.

Attention deficit and hyperactivity disorder (ADHD) is a prevalent neurodevelopmental condition, impacting approximately 10% of children globally. A significant proportion, around 30–50%, of those diagnosed during childhood continue to manifest ADHD symptoms into adulthood, with 2–5% of adults experiencing the condition. The existing diagnostic framework for ADHD relies on clinical assessments and interviews conducted by healthcare professionals. This diagnostic process is complicated by the disorder’s overlap in symptoms and frequent comorbidities with other neurodevelopmental conditions, particularly bipolar disorder during its manic phase, adding complexity to achieving accurate and timely diagnoses. Despite extensive efforts to identify reliable biomarkers that could enhance the clinical diagnosis, this objective remains elusive. In this study, Raman spectroscopy, combined with multivariate statistical methods, was employed to construct a model based on the analysis of blood serum samples. The developed partial least-squares discriminant analysis (PLS-DA) model demonstrated an ability to differentiate between individuals with ADHD, healthy individuals, and those diagnosed with bipolar disorder in the manic phase, with a total accuracy of 97.4%. The innovative approach in this model involves utilizing the entire Raman spectrum, within the 450–1720 cm⁻¹ range, as a comprehensive representation of the biochemical blood serum setting, thus serving as a holistic spectroscopic biomarker. This method circumvents the necessity to pinpoint specific chemical substances associated with the disorders, eliminating the reliance on specific molecular biomarkers. Moreover, the developed model relies on a sensitive and reliable technique that is cost-effective and rapid, presenting itself as a promising complementary diagnostic tool for clinical settings. The potential for Raman spectroscopy to contribute to the diagnostic process suggests a step forward in addressing the challenges associated with accurately identifying and distinguishing ADHD from other related conditions. Full article

(This article belongs to the Special Issue Feature Papers in Spectroscopy Journal)

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16 pages, 82983 KiB

Open AccessArticle

Why Are the Early Gothic Murals in St. Jacob’s Church in Ormož, Slovenia, Almost Entirely Black?

by Anabelle Kriznar, Katja Kavkler and Sabina Dolenec

Spectrosc. J. 2024, 2(2), 37-52; https://doi.org/10.3390/spectroscj2020003 - 13 Apr 2024

In St. Jacob’s parish church in Ormož, Slovenia, mural paintings from around 1350–1370 are partially conserved in the northeastern corner of the main nave. They are almost completely black, indicating a large-scale pigment degradation. They were studied as a part of a larger [...] Read more.

In St. Jacob’s parish church in Ormož, Slovenia, mural paintings from around 1350–1370 are partially conserved in the northeastern corner of the main nave. They are almost completely black, indicating a large-scale pigment degradation. They were studied as a part of a larger research project aiming to identify materials applied and their possible degradation. First, they were studied in situ, and next, extracted samples of plaster, pigments, and colour layers were analysed by optical microscopy, Raman spectroscopy, FTIR spectroscopy, SEM-EDS, and XRD. Haematite, green earth, malachite, azurite, and tenorite were identified, showing that azurite and perhaps also malachite degraded to black tenorite, probably due to their fine grinding and their application directly on the fresh plaster. The plaster is made with small and large amounts of aggregate with mostly quartz with some impurities, which makes it fragile. The original appearance of these murals was of bright blue and green colours. Full article

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4 pages, 173 KiB

Open AccessEditorial

The Context of the Spectroscopy Journal—Today and in the Future

by Clemens Burda

Spectrosc. J. 2024, 2(1), 33-36; https://doi.org/10.3390/spectroscj2010002 - 15 Mar 2024

As a scientific discipline at the intersection between physics and chemistry, spectroscopy is historically grounded in curiosity-driven experiments of splitting sunlight into its spectral components [...] Full article

32 pages, 8504 KiB

Open AccessReview

Laser-Induced Breakdown Spectroscopy Applied to Elemental Analysis of Aqueous Solutions—A Comprehensive Review

by Nils Schlatter and Bernd G. Lottermoser

Spectrosc. J. 2024, 2(1), 1-32; https://doi.org/10.3390/spectroscj2010001 - 17 Jan 2024

Laser-induced breakdown spectroscopy (LIBS) has evolved considerably in recent years, particularly the application of portable devices for the elemental analysis of solids in the field. However, aqueous analysis using LIBS instruments, either in the laboratory or in the field, is rather rare, despite [...] Read more.

Laser-induced breakdown spectroscopy (LIBS) has evolved considerably in recent years, particularly the application of portable devices for the elemental analysis of solids in the field. However, aqueous analysis using LIBS instruments, either in the laboratory or in the field, is rather rare, despite extensive research on the topic since 1984. Thus, our comprehensive review aims to provide a clear overview of this research to offer guidance to new users. To achieve this, we examined the literature published between 1984 and 2023, comparing various settings and parameters in a database. There are four different categories of LIBS instruments: laboratory-based, online, portable, and telescopic. Additionally, there are four main categories of sample preparation techniques: liquid bulk, liquid-to-solid conversion, liquid-to-aerosol conversion, and hydride generation. Various experimental setups are also in use, such as double-pulse. Moreover, different acquisition settings significantly influence the sensitivity and therefore the detection limits. Documentation of the different methods of sample preparation and experimental settings, along with their main advantages and disadvantages, can help new users make an informed choice for a particular desired application. In addition, the presentation of median detection limits per element in a periodic table of elements highlights possible research gaps and future research opportunities by showing which elements are rarely or not analysed and for which new approaches in sample preparation are required to lower the detection limits. Full article

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19 pages, 1805 KiB

Open AccessReview

Spectroscopic Ellipsometry: Advancements, Applications and Future Prospects in Optical Characterization

by Grazia Giuseppina Politano and Carlo Versace

Spectrosc. J. 2023, 1(3), 163-181; https://doi.org/10.3390/spectroscj1030014 - 06 Dec 2023

Spectroscopic ellipsometry (SE), a non-invasive optical technique, is a powerful tool for characterizing surfaces, interfaces, and thin films. By analyzing the change in the polarization state of light upon reflection or transmission through a sample, ellipsometry provides essential parameters such as thin film [...] Read more.

Spectroscopic ellipsometry (SE), a non-invasive optical technique, is a powerful tool for characterizing surfaces, interfaces, and thin films. By analyzing the change in the polarization state of light upon reflection or transmission through a sample, ellipsometry provides essential parameters such as thin film thickness (t) and optical constants (n, k). This review article discusses the principles of ellipsometry, including the measurement of key values ∆ and Ψ, and the complex quantity ρ. The article also presents the Fresnel equations for s and p polarizations and the importance of oblique angles of incidence in ellipsometry. Data analysis in ellipsometry is explored, including the determination of bandgap and data referencing the electrical properties of materials. The article emphasizes the importance of choosing the appropriate models to fit ellipsometric data accurately, with examples of the Cauchy and Lorentz models. Additionally, the Kramers–Kronig relations are introduced, illustrating the connection between real and imaginary components of optical constants. The review underscores the significance of ellipsometry as a non-destructive and versatile technique for material characterization across a wide range of applications. Full article

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11 pages, 1090 KiB

Open AccessArticle

Performance Evaluation of Fiber Near-Infrared (NIR) Optic Probes for Quality Control of Curd Hardness in Cheese Produced by Spray-Dried Milk

by Lesther Meza, Ricardo S. Aleman, Jhunior Marcia, Ajitesh Yadav and Manuel Castillo

Spectrosc. J. 2023, 1(3), 152-162; https://doi.org/10.3390/spectroscj1030013 - 20 Nov 2023

This study aims to provide the dairy industry with a direct control model focused on milk coagulation by using multifiber probes to determine parameters in the curding process, such as cutting time, at a lower cost. The main objective of the research is [...] Read more.

This study aims to provide the dairy industry with a direct control model focused on milk coagulation by using multifiber probes to determine parameters in the curding process, such as cutting time, at a lower cost. The main objective of the research is to confirm that a multifiber NIR light scattering probe can be used to predict the elastic modulus of curd during milk coagulation in cheese production. Two randomized complete block designs were used with a 3 × 3 factorial arrangement of three protein levels (3%, 3.5% and 4%) and three wavelengths (870 nm, 880 nm and 890 nm). Using a multifiber probe at a wavelength of 880 nm allowed obtaining a better optical response of the sensor during enzymatic milk coagulation than the 870 nm. It showed greater sensitivity to variations in the protein content of the milk and lower variation in the response. The multifiber probe at a wavelength of 880 nm generated a NIR light backscatter profile like those obtained with other systems. The results showed that the prediction model parameters had a variation as a function of the protein content, which opens the possibility of improving the prediction model’s performance substantially. Furthermore, the initial voltage obtained with the probe responded linearly to the different protein levels in milk. This fact would make it possible, at least theoretically, to estimate protein concentration with the same inline probe for G’ determination, facilitating the incorporation of a corrective protein factor in the prediction models using a single instrument. Full article

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15 pages, 4871 KiB

Open AccessArticle

Optimal Conditions for a Multimode Laser Diode with Delayed Optical Feedback in Terahertz Time-Domain Spectroscopy

by Kenji Wada, Tokihiro Kitagawa, Tetsuya Matsuyama, Koichi Okamoto and Fumiyoshi Kuwashima

Spectrosc. J. 2023, 1(3), 137-151; https://doi.org/10.3390/spectroscj1030012 - 04 Nov 2023

Recent studies have indicated that terahertz time-domain spectroscopy (THz-TDS) can stably and efficiently acquire output spectra using an affordable and compact multimode laser diode (MMLD) with delayed optical feedback as the light source. This research focused on a numerical analysis of the optimal [...] Read more.

Recent studies have indicated that terahertz time-domain spectroscopy (THz-TDS) can stably and efficiently acquire output spectra using an affordable and compact multimode laser diode (MMLD) with delayed optical feedback as the light source. This research focused on a numerical analysis of the optimal conditions for employing an MMLD with delayed optical feedback (a chaotic oscillating laser diode) in THz-TDS utilizing multimode rate equations. The findings revealed that the intermittent chaotic output generated by the MMLD, characterized by concurrent picosecond pulse oscillations lasting several tens of picoseconds, proved to be highly effective for THz-TDS. By appropriately setting the amounts for the injection current and optical feedback and the delay time for the optical feedback, intermittent chaotic oscillation could be attained within a considerably broad parameter range. The generation of intermittent chaotic oscillations was confirmed by observing their characteristic asymmetric spectral shapes. Moreover, both the MMLD output spectrum and the THz-TDS output spectrum exhibited consistently stable shapes at the microsecond scale, demonstrating the attractor properties inherent in an MMLD with delayed optical feedback. Full article

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16 pages, 4899 KiB

Open AccessArticle

A Spectroscopy-Based Multi-Analytical Approach for Studies in Conservation: Decorations in the Alexander Palace (Tsarskoye Selo)

by Marilena Ricci, Federico Sebastiani, Maurizio Becucci, Mikhail Rogozny and Vadim Parfenov

Spectrosc. J. 2023, 1(3), 121-136; https://doi.org/10.3390/spectroscj1030011 - 20 Oct 2023

We studied the painted decorations found during recent restoration work in the Alexander Palace in Tsarskoye Selo. Optical/laser spectroscopic methods were applied to obtain a characterization of the materials, pigments, and binders in use and, possibly, their degradation. We analyzed samples of the [...] Read more.

We studied the painted decorations found during recent restoration work in the Alexander Palace in Tsarskoye Selo. Optical/laser spectroscopic methods were applied to obtain a characterization of the materials, pigments, and binders in use and, possibly, their degradation. We analyzed samples of the original Art Nouveau style decoration that was detached in 2019 during conservation work at the State Office of Emperor Nicholas II. A combination of Raman microscopy, infrared spectroscopy, and elemental analysis (obtained from the optical emission following laser plasma formation) allowed us to obtain detailed information on the materials used. The precious pigments of the artist’s green-blue palette and the binder used (drying oil) were identified. A mixture of blue (Prussian blue and ultramarine blue), white (lead white and barium white), and yellow (chrome yellow and zinc yellow) pigments determined the different blue hues used. The use of bronze paint in the dark blue area, which was identified as a brass powder applied with a drying oil as a binder, was also demonstrated. Full article

(This article belongs to the Special Issue Feature Papers in Spectroscopy Journal)

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10 pages, 2472 KiB

Open AccessArticle

Rotational Isomerism of the Side Chains of Hydroxypropyl Cellulose in Aqueous Solution Observed Using Attenuated Total Reflectance Infrared Spectroscopy

by Mark A. Davies

Spectrosc. J. 2023, 1(3), 111-120; https://doi.org/10.3390/spectroscj1030010 - 13 Oct 2023

Etherified cellulose derivatives, in contrast to cellulose, are soluble in water at room temperature and have a wide variety of applications. One of their most important characteristics is their decrease in solubility with temperature. The objective of this work was to study the [...] Read more.

Etherified cellulose derivatives, in contrast to cellulose, are soluble in water at room temperature and have a wide variety of applications. One of their most important characteristics is their decrease in solubility with temperature. The objective of this work was to study the rotational isomerism of the side chains of hydroxypropyl cellulose (HPC) in aqueous solution as sole solute and in the presence of chloride, sulfate, and barium ions as a function of temperature. Infrared Attenuated Total Reflectance spectroscopy was used to measure changes in the side-chain rotational isomerism using the structurally sensitive methylene wagging region as the probe. Decreases in end-gauche and kink conformers were observed. Principal component analysis revealed the presence of multiple forms of HPC at higher molecular weight. The precipitation of HPC as the temperature was increased was accompanied by a reduction in the numbers of end-gauche and kink conformers. Full article

(This article belongs to the Special Issue Application of Molecular Spectroscopy in Coordination and Supramolecular Chemistry)

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13 pages, 3247 KiB

Open AccessArticle

Effect of Alkaline Salts on Pyrolyzed Solid Wastes in Used Edible Oils: An Attenuated Total Reflectance Analysis of Surface Compounds as a Function of the Temperature

by Francisca Romero-Sarria, Concepción Real, José Manuel Córdoba, María Carmen Hidalgo and María Dolores Alcalá

Spectrosc. J. 2023, 1(2), 98-110; https://doi.org/10.3390/spectroscj1020009 - 13 Sep 2023

Biochars obtained via the pyrolysis of biomass are very attractive materials from the point of view of their applications and play key roles in the current energy context. The characterization of these carbonaceous materials is crucial to determine their field of application. In [...] Read more.

Biochars obtained via the pyrolysis of biomass are very attractive materials from the point of view of their applications and play key roles in the current energy context. The characterization of these carbonaceous materials is crucial to determine their field of application. In this work, the pyrolysis of a non-conventional biomass (solid wastes in used edible oils) was investigated. The obtained biochars were characterized using conventional techniques (TG, XRD, and SEM-EDX), and a deep analysis via ATR-FTIR was performed. This spectroscopic technique, which is a rapid and powerful tool that is well adapted to study carbon-based materials, was employed to determine the effect of temperature on the nature of functional groups on the surface. Moreover, the water washing of the raw sample (containing important quantities of inorganic salts) before pyrolysis evidenced that the inorganic salts act as catalysts in the biomass degradation and influence the degree of condensation (DOC) of PAH. Moreover, it was observed that these salts contribute to the retention of oxygenated compounds on the surface of the solid. Full article

(This article belongs to the Special Issue Feature Papers in Spectroscopy Journal)

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12 pages, 1266 KiB

Open AccessArticle

Narrow-Linewidth Pr:YLF Laser for High-Resolution Raman Trace Gas Spectroscopy

by Charuka Muktha Arachchige and Andreas Muller

Spectrosc. J. 2023, 1(2), 86-97; https://doi.org/10.3390/spectroscj1020008 - 23 Aug 2023

Spontaneous Raman gas spectroscopy, which stands out as a versatile chemical identification tool, typically relies on frequency-doubled infrared laser sources to deliver the high power and narrow linewidth needed to achieve chemical detection at trace concentrations. The relatively low efficiency and high complexity [...] Read more.

Spontaneous Raman gas spectroscopy, which stands out as a versatile chemical identification tool, typically relies on frequency-doubled infrared laser sources to deliver the high power and narrow linewidth needed to achieve chemical detection at trace concentrations. The relatively low efficiency and high complexity of these lasers, however, can make them challenging to integrate into field-deployable instruments. Additionally, the frequency doubling prevents the utilization of circulating laser power for Raman enhancement. A diode-pumped Pr:YLF laser was investigated as an alternative narrow-band light source that could potentially realize a more portable Raman scattering system. When operated with an intracavity etalon, the laser realized a linewidth of 0.5 cm

^{- 1}

with a green output power of 0.37 W and circulating power of 16 W when pumped with 3.1 W from a blue diode laser. Trace detection at atmospheric pressure with a high degree of spectral discrimination was demonstrated by resolving overlapping N

_{2}

/CO and CO

_{2}

/N

_{2}

O Raman bands in air. Full article

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14 pages, 3347 KiB

Open AccessArticle

Dielectric Stability of Triton X-100-Based Tissue-Mimicking Materials for Microwave Imaging

by Mariana Relva and Susana Devesa

Spectrosc. J. 2023, 1(2), 72-85; https://doi.org/10.3390/spectroscj1020007 - 03 Aug 2023

Microwave imaging is an emerging technology, and has been proposed for various applications, namely as an alternative diagnostic technology. Microwave imaging explores the dielectric contrast of target tissues, enabling diagnosis based on the differences in dielectric properties between healthy and diseased tissues, with [...] Read more.

Microwave imaging is an emerging technology, and has been proposed for various applications, namely as an alternative diagnostic technology. Microwave imaging explores the dielectric contrast of target tissues, enabling diagnosis based on the differences in dielectric properties between healthy and diseased tissues, with low cost, portability and non-ionizing radiation as its main advantages, constituting an alternative to various imaging technologies for diagnosing and monitoring. Before clinical trials of microwave imaging devices for the study of dielectric properties, phantoms are used, mimicking the materials of tissues and simulating the electric properties of human tissues, for device validation. The purpose of this work was to prepare and perform dielectric characterization of mimicking materials for the development of an anthropomorphic phantom of the human ankle with realistic dielectric and anatomic properties. The biological tissues targeted in this investigation were the skin, muscle, cortical bone, trabecular bone and fat, with the mimicking materials prepared using Triton X-100, sodium chloride and distilled water. The dielectric characterization was performed using a coaxial probe, operating at frequencies between 0.5 and 4.0 GHz. Since the stability of the dielectric properties of mimicking materials is one of their main properties, the dielectric characterization was repeated after 15 and 35 days. Full article

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7 pages, 2588 KiB

Open AccessCommunication

Light-Induced Condensates Show Accumulation-Prone and Less Dynamic Properties in the Nucleus Compared to the Cytoplasm

by Yuta Hamada and Akira Kitamura

Spectrosc. J. 2023, 1(2), 65-71; https://doi.org/10.3390/spectroscj1020006 - 10 Jul 2023

Biomolecular condensates, including membraneless organelles, are ubiquitously observed in subcellular compartments. However, the accumulation and dynamic properties of arbitrarily induced condensates remain elusive. Here, we show the size, amount, and dynamic properties of subcellular condensates using various fluorescence spectroscopic imaging analyses. Spatial image [...] Read more.

Biomolecular condensates, including membraneless organelles, are ubiquitously observed in subcellular compartments. However, the accumulation and dynamic properties of arbitrarily induced condensates remain elusive. Here, we show the size, amount, and dynamic properties of subcellular condensates using various fluorescence spectroscopic imaging analyses. Spatial image correlation spectroscopy showed that the size of blue-light-induced condensates of cryptochrome 2-derived oligomerization tag (CRY2olig) tagged with a red fluorescent protein in the nucleus was not different from that in the cytoplasm. Fluorescence intensity measurements showed that the condensates in the nucleus were more prone to accumulation than those in the cytoplasm. Single-particle tracking analysis showed that the condensates in the nucleus are predisposed to have stationary dynamics compared to those in the cytoplasm. Therefore, the subcellular compartment may, in part, affect the characteristics of self-recruitment of biomolecules in the condensates and their movement property. Full article

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16 pages, 2372 KiB

Open AccessArticle

Barrier to Methyl Internal Rotation and Equilibrium Structure of 2-Methylthiophene Determined by Microwave Spectroscopy

by Kenneth J. Koziol, Hamza El Hadki, Arne Lüchow, Natalja Vogt, Jean Demaison and Ha Vinh Lam Nguyen

Spectrosc. J. 2023, 1(1), 49-64; https://doi.org/10.3390/spectroscj1010005 - 30 May 2023

Cited by 2

The microwave spectrum of 2-methylthiophene was recorded in a frequency range from 2 to 26.5 GHz using a molecular-jet Fourier transform microwave spectrometer with a Fabry–Pérot type resonator chamber and coaxial arrangement of the resonator and the molecular beam. Measuring and assigning spectra [...] Read more.

The microwave spectrum of 2-methylthiophene was recorded in a frequency range from 2 to 26.5 GHz using a molecular-jet Fourier transform microwave spectrometer with a Fabry–Pérot type resonator chamber and coaxial arrangement of the resonator and the molecular beam. Measuring and assigning spectra of the ³⁴S and ¹³C isotopologues allowed the determination of the semiexperimental equilibrium structure (

r_{e}^{SE}

). Comparing the structure to that of thiophene revealed a decrease in the ∠(S−C2−C3) angle from 111.595(6)° to 111.37(1)° by addition of the methyl group to the C(2) position, as well as an increase in the S−C2 bond length from 1.7102(1) Å to 1.7219(2) Å. A–E splittings from internal rotation of the methyl group were observed, and the V₃ potential in the vibrational ground state was determined to be 197.7324(18) cm⁻¹. The V₃ value and the rotational constants A, B, C were calculated with a large number of different methods and basis sets for benchmarking purposes by comparing them to the fitted parameters. The V₃ value was also compared to those of other thiophene and furan derivatives to gain a better understanding of the steric and electrostatic effects in these classes of compounds. Full article

(This article belongs to the Special Issue Feature Papers in Spectroscopy Journal)

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12 pages, 1237 KiB

Open AccessArticle

Age-Related Fourier-Transform Infrared Spectroscopic Changes in Protein Conformation in an Aging Model of Human Dermal Fibroblasts

by Cláudia Martins, Idália Almeida, Sandra Rebelo, Sandra Magalhães and Alexandra Nunes

Spectrosc. J. 2023, 1(1), 37-48; https://doi.org/10.3390/spectroscj1010004 - 24 Apr 2023

Cited by 2

The loss of proteostasis, which results in the accumulation of misfolded proteins, is one of the hallmarks of aging and is frequently associated with the aging process. Fibroblasts are a cellular model widely used in the study of aging and can mimic the [...] Read more.

The loss of proteostasis, which results in the accumulation of misfolded proteins, is one of the hallmarks of aging and is frequently associated with the aging process. Fibroblasts are a cellular model widely used in the study of aging and can mimic the loss of proteostasis that occurs in the human body. When studying human aging using fibroblasts, two approaches can be used: fibroblasts from the same donor aged in vitro until senescence or fibroblasts from donors of different ages. A previous study by our group showed that the first approach can be used in the study of aging. Thus, this work aimed to study the spectroscopic profile of human dermal fibroblasts from four donors of different ages using Fourier-transform infrared spectroscopy to identify changes in protein conformation and to compare results with those obtained in the previous study. Partial least squares regression analysis and peak intensity analysis suggested that fibroblasts from older donors were characterized by an increase in the levels of antiparallel β-sheets and a decrease in intermolecular β-sheets, in agreement with our previous results. Full article

(This article belongs to the Special Issue Feature Papers in Spectroscopy Journal)

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9 pages, 833 KiB

Open AccessCommunication

Diode Laser Overtone Spectroscopy of Methyl Iodide at 850 nm

by Alessandro Lucchesini

Spectrosc. J. 2023, 1(1), 28-36; https://doi.org/10.3390/spectroscj1010003 - 12 Apr 2023

Using Tunable Diode Laser Absorption Spectroscopy (TDLAS), 82 CH

_{3}

I overtone absorption lines were detected for the first time in the range between 11,660 and 11,840 cm

^{- 1}

(844–857 nm), with strengths estimated around

10^{- 27}

–10

^{- 26}

cm/molecule. [...] Read more.

Using Tunable Diode Laser Absorption Spectroscopy (TDLAS), 82 CH

_{3}

I overtone absorption lines were detected for the first time in the range between 11,660 and 11,840 cm

^{- 1}

(844–857 nm), with strengths estimated around

10^{- 27}

–10

^{- 26}

cm/molecule. The lines were measured utilizing commercial heterostructure F–P type diode lasers, multipass cells, and wavelength modulation spectroscopy with the second harmonic detection technique. A high modulation amplitude approach was adopted for the analysis of the line shapes. Self-broadening coefficients were obtained for two lines. Full article

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25 pages, 5230 KiB

Open AccessFeature PaperReview

Interpreting the Microwave Spectra of Diatomic Molecules

by Cory C. Pye

Spectrosc. J. 2023, 1(1), 3-27; https://doi.org/10.3390/spectroscj1010002 - 08 Feb 2023

Cited by 1

A brief review of the theory of the rigid rotor and its application to microwave spectroscopy is given. By careful selection of examples, procedures are given for the analysis of successively more complicated spectra, and the theory is extended to the harmonic nonrigid [...] Read more.

A brief review of the theory of the rigid rotor and its application to microwave spectroscopy is given. By careful selection of examples, procedures are given for the analysis of successively more complicated spectra, and the theory is extended to the harmonic nonrigid rotor and anharmonic nonrigid rotor when needed. The microwave spectra of carbon monoxide, and of some alkali halides, provide excellent examples for analysis and for student exercises. Full article

(This article belongs to the Special Issue Feature Papers in Spectroscopy Journal)

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2 pages, 13412 KiB

Open AccessEditorial

Spectroscopy Journal—Open Access Journal on Spectroscopy

by Clemens Burda

Spectrosc. J. 2023, 1(1), 1-2; https://doi.org/10.3390/spectroscj1010001 - 27 Dec 2022

Cited by 1

It is my great pleasure to inaugurate the new MDPI journal, [...] Full article

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Special Issue in Spectroscopy Journal

Spectroscopic Methods for Biological Kinetics Guest Editor: Dimitri Svistunenko
Deadline: 30 April 2024

Special Issue in Spectroscopy Journal

Feature Papers in Spectroscopy JournalGuest Editor: Clemens Burda
Deadline: 15 July 2024

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Deadline: 30 September 2024

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