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10 pages, 2826 KiB

Open AccessArticle

Molecular Recalcitrance of Hair Passing the Digestive System of a Canid

by Johannes Tintner, Jennifer Hatlauf, Heidi Weber and József Lanszki

Molecules 2020, 25(19), 4404; https://doi.org/10.3390/molecules25194404 - 25 Sep 2020

Viewed by 2362

Abstract

Hair is an important component in scat that is commonly used for prey analyses in carnivores. Chemically, hair predominately consists of keratin. The recalcitrant fiber protein is degraded in nature only by a few insects and soil microorganisms. Common proteases such as pepsin [...] Read more.

Hair is an important component in scat that is commonly used for prey analyses in carnivores. Chemically, hair predominately consists of keratin. The recalcitrant fiber protein is degraded in nature only by a few insects and soil microorganisms. Common proteases such as pepsin do not decompose keratin. Infrared spectroscopy was used to detect chemical differences caused by pretreatment and fate of hairs. Three sample sets were compared: original untreated hair, original milled hair, and hairs extracted from scats of golden jackals (Canis aureus L.). The results revealed that only milling affected the infrared spectral pattern, whereas digestion had no impact. Moreover, hairs from different species (e.g., boar) could be distinguished due to their spectral characteristics. They did not change through the passage of the digestive system. Full article

(This article belongs to the Special Issue Practical Applications of Molecular Spectroscopy)

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10 pages, 1704 KiB

Open AccessArticle

Bichromatic Photoassociation Spectroscopy for the Determination of Rotational Constants of Cs₂ 0 u + Long-Range State below the 6S_1/2 + 6P_1/2 Asymptote

by Jizhou Wu, Jie Ma, Yuqing Li, Wenliang Liu, Peng Li and Vladimir B. Sovkov

Molecules 2020, 25(17), 3963; https://doi.org/10.3390/molecules25173963 - 31 Aug 2020

Viewed by 1806

Abstract

This article demonstrates new observation of the high-resolution ro-vibrational bichromatic photoassociation spectra (BPAS) of Cs₂ in the

0_{u}^{+}

long-range state below the asymptotes 6S_1/2 + 6P_1/2. By combining with a modulation spectroscopic technique, precise references of the [...] Read more.

This article demonstrates new observation of the high-resolution ro-vibrational bichromatic photoassociation spectra (BPAS) of Cs₂ in the

0_{u}^{+}

long-range state below the asymptotes 6S_1/2 + 6P_1/2. By combining with a modulation spectroscopic technique, precise references of the frequency differences have been engineered through the BPAS, with which the rotational constants of low-lying vibrational levels of the Cs₂

0_{u}^{+}

long-range state have been accurately determined by fitting the frequency differences to the non-rigid-rotor model. The rotational constants for the newly observed seven ro-vibrational levels are summarized and disagreement for the level ῦ = 498 is clarified. The rotational constants of different vibrational levels demonstrate strong perturbations of the related energy structures. A simple analysis is performed and shows good agreement with experimental results. Full article

(This article belongs to the Special Issue Practical Applications of Molecular Spectroscopy)

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12 pages, 5549 KiB

Open AccessArticle

Photochemical α-Cleavage Reaction of 3’,5’-Dimethoxybenzoin: A Combined Time-Resolved Spectroscopy and Computational Chemistry Study

by Yuanchun Li, Xiting Zhang, Zhiping Yan, Lili Du, Wenjian Tang and David Lee Phillips

Molecules 2020, 25(15), 3548; https://doi.org/10.3390/molecules25153548 - 03 Aug 2020

Cited by 1 | Viewed by 3199

Abstract

Benzoin is one of the most commonly used photoinitiators to induce free radical polymerization. Here, improved benzoin properties could be accomplished by the introduction of two methoxy substituents, leading to the formation of 3’,5’-dimethoxybenzoin (DMB) which has a higher photo-cleavage quantum yield (0.54) [...] Read more.

Benzoin is one of the most commonly used photoinitiators to induce free radical polymerization. Here, improved benzoin properties could be accomplished by the introduction of two methoxy substituents, leading to the formation of 3’,5’-dimethoxybenzoin (DMB) which has a higher photo-cleavage quantum yield (0.54) than benzoin (0.35). To elucidate the underlying reaction mechanisms of DMB and obtain direct information of the transient species involved, femtosecond transient absorption (fs-TA) and nanosecond transient absorption (ns-TA) spectroscopic experiments in conjunction with density functional theory/time-dependent density functional theory (DFT/TD-DFT) calculations were performed. It was found that the photo-induced α-cleavage (Norrish Type I reaction) of DMB occurred from the nπ* triplet state after a rapid intersystem crossing (ISC) process (7.6 ps), leading to the generation of phenyl radicals on the picosecond time scale. Compared with Benzoin, DMB possesses two methoxy groups which are able to stabilize the alcohol radical and thus result in a stronger driving force for cleavage and a higher quantum yield of photodissociation. Two stable conformations (cis-DMB and trans-DMB) at ground state were found via DFT calculations. The influence of the intramolecular hydrogen bond on the α-cleavage of DMB was elaborated. Full article

(This article belongs to the Special Issue Practical Applications of Molecular Spectroscopy)

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18 pages, 4048 KiB

Open AccessFeature PaperArticle

Laser-Plasma Spectroscopy of Hydroxyl with Applications

by Christian G. Parigger, Christopher M. Helstern, Benjamin S. Jordan, David M. Surmick and Robert Splinter

Molecules 2020, 25(4), 988; https://doi.org/10.3390/molecules25040988 - 22 Feb 2020

Cited by 11 | Viewed by 3989

Abstract

This article discusses laser-induced laboratory-air plasma measurements and analysis of hydroxyl (OH) ultraviolet spectra. The computations of the OH spectra utilize line strength data that were developed previously and that are now communicated for the first time. The line strengths have been utilized [...] Read more.

This article discusses laser-induced laboratory-air plasma measurements and analysis of hydroxyl (OH) ultraviolet spectra. The computations of the OH spectra utilize line strength data that were developed previously and that are now communicated for the first time. The line strengths have been utilized extensively in interpretation of recorded molecular emission spectra and have been well-tested in laser-induced fluorescence applications for the purpose of temperature inferences from recorded data. Moreover, new experiments with Q-switched laser pulses illustrate occurrence of molecular recombination spectra for time delays of the order of several dozen of microseconds after plasma initiation. The OH signals occur due to the natural humidity in laboratory air. Centrifugal stretching of the Franck-Condon factors and r-centroids are included in the process of determining the line strengths that are communicated as a Supplementary File. Laser spectroscopy applications of detailed OH computations include laser-induced plasma and combustion analyses, to name but two applications. This work also includes literature references that address various diagnosis applications. Full article

(This article belongs to the Special Issue Practical Applications of Molecular Spectroscopy)

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10 pages, 1969 KiB

Open AccessFeature PaperArticle

The Plasma Spectroscopic Study of Dergaon Meteorite, India

by Abhishek K. Rai, Jayanta K. Pati, Christian G. Parigger, Sonali Dubey, Awadhesh K. Rai, Balen Bhagabaty, Amulya C. Mazumdar and Kalpana Duorah

Molecules 2020, 25(4), 984; https://doi.org/10.3390/molecules25040984 - 22 Feb 2020

Cited by 11 | Viewed by 3027

Abstract

Meteorites are the recoverable portions of asteroids that reach the surface of the Earth. Meteorites are rare extraterrestrial objects studied extensively to improve our understanding of planetary evolution. In this work, we used calibration-free laser-induced breakdown spectroscopy (CF-LIBS) to evaluate the quantitative elemental [...] Read more.

Meteorites are the recoverable portions of asteroids that reach the surface of the Earth. Meteorites are rare extraterrestrial objects studied extensively to improve our understanding of planetary evolution. In this work, we used calibration-free laser-induced breakdown spectroscopy (CF-LIBS) to evaluate the quantitative elemental and molecular analyses of the Dergaon meteorite, a H 4-5 chondrite fall sample from Assam, India. Spectral signatures of H, N, O, Na, Mg, Al, Si, P, K, Ca, Ti, Cr, Mn, Fe, Co, Ni, andIrweredetected. Along with the atomic emission, this work reports the molecular emission from FeO molecules. The concentration of the measured elements obtained using CF-LIBS is in close agreement with earlier reports. The elements H, N, and O and their concentrations are estimated by using CF-LIBS for the first time. This study applies laser spectroscopy to establish the presence of Ni, Cr, Co, and Ir in meteorites. The elemental analysis forms the basis for the establishment of the potential molecular composition of the Dergaon meteorite. Moreover, the elemental analysis approach bodes well for in-situ analyses of extraterrestrial objects including applications in planetary rover missions. Full article

(This article belongs to the Special Issue Practical Applications of Molecular Spectroscopy)

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13 pages, 1724 KiB

Open AccessArticle

Laser-Plasma Spatiotemporal Cyanide Spectroscopy and Applications

by Christian G. Parigger, Christopher M. Helstern, Benjamin S. Jordan, David M. Surmick and Robert Splinter

Molecules 2020, 25(3), 615; https://doi.org/10.3390/molecules25030615 - 31 Jan 2020

Cited by 15 | Viewed by 3300

Abstract

This article reports new measurements of laser-induced plasma hypersonic expansion measurements of diatomic molecular cyanide (CN). Focused, high-peak-power 1064 nm Q-switched radiation of the order of 1 TW/cm

^{2}

generated optical breakdown plasma in a cell containing a 1:1 molar gas mixture of [...] Read more.

This article reports new measurements of laser-induced plasma hypersonic expansion measurements of diatomic molecular cyanide (CN). Focused, high-peak-power 1064 nm Q-switched radiation of the order of 1 TW/cm

^{2}

generated optical breakdown plasma in a cell containing a 1:1 molar gas mixture of N

_{2}

and CO

_{2}

at a fixed pressure of 1.1 × 10

^{5}

Pascal and in a 100 mL/min flow of the mixture. Line-of-sight (LOS) analysis of recorded molecular spectra indicated the outgoing shockwave at expansion speeds well in excess of Mach 5. Spectra of atomic carbon confirmed increased electron density near the shockwave, and, equally, molecular CN spectra revealed higher excitation temperature near the shockwave. Results were consistent with corresponding high-speed shadowgraphs obtained by visualization with an effective shutter speed of 5 nanoseconds. In addition, LOS analysis and the application of integral inversion techniques allow inferences about the spatiotemporal plasma distribution. Full article

(This article belongs to the Special Issue Practical Applications of Molecular Spectroscopy)

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12 pages, 2762 KiB

Open AccessArticle

Enhancing Double-Beam Laser Tweezers Raman Spectroscopy (LTRS) for the Photochemical Study of Individual Airborne Microdroplets

by Jovanny A. Gómez Castaño, Luc Boussekey, Jean P. Verwaerde, Myriam Moreau and Yeny A. Tobón

Molecules 2019, 24(18), 3325; https://doi.org/10.3390/molecules24183325 - 12 Sep 2019

Cited by 7 | Viewed by 3187

Abstract

A new device and methodology for vertically coupling confocal Raman microscopy with optical tweezers for the in situ physico- and photochemical studies of individual microdroplets (Ø ≤ 10 µm) levitated in air is presented. The coupling expands the spectrum of studies performed with [...] Read more.

A new device and methodology for vertically coupling confocal Raman microscopy with optical tweezers for the in situ physico- and photochemical studies of individual microdroplets (Ø ≤ 10 µm) levitated in air is presented. The coupling expands the spectrum of studies performed with individual particles using laser tweezers Raman spectroscopy (LTRS) to photochemical processes and spatially resolved Raman microspectroscopy on airborne aerosols. This is the first study to demonstrate photochemical studies and Raman mapping on optically levitated droplets. By using this configuration, photochemical reactions in aerosols of atmospheric interest can be studied on a laboratory scale under realistic conditions of gas-phase composition and relative humidity. Likewise, the distribution of photoproducts within the drop can also be observed with this setup. The applicability of the coupling system was tested by studying the photochemical behavior of microdroplets (5 µm < Ø < 8 µm) containing an aqueous solution of sodium nitrate levitated in air and exposed to narrowed UV radiation (254 ± 25 nm). Photolysis of the levitated NaNO₃ microdroplets presented photochemical kinetic differences in comparison with larger NaNO₃ droplets (40 µm < Ø < 80 µm), previously photolyzed using acoustic traps, and heterogeneity in the distribution of the photoproducts within the drop. Full article

(This article belongs to the Special Issue Practical Applications of Molecular Spectroscopy)

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Review

Jump to: Research

33 pages, 9982 KiB

Open AccessReview

Spectroscopic Methods Used in Implant Material Studies

by Sławomir Lach, Przemysław Jurczak, Natalia Karska, Agnieszka Kubiś, Aneta Szymańska and Sylwia Rodziewicz-Motowidło

Molecules 2020, 25(3), 579; https://doi.org/10.3390/molecules25030579 - 29 Jan 2020

Cited by 5 | Viewed by 3621

Abstract

It is recognized that interactions between most materials are governed by their surface properties and manifest themselves at the interface formed between them. To gain more insight into this thin layer, several methods have been deployed. Among them, spectroscopic methods have been thoroughly [...] Read more.

It is recognized that interactions between most materials are governed by their surface properties and manifest themselves at the interface formed between them. To gain more insight into this thin layer, several methods have been deployed. Among them, spectroscopic methods have been thoroughly evaluated. Due to their exceptional sensitivity, data acquisition speed, and broad material tolerance they have been proven to be invaluable tools for surface analysis, used by scientists in many fields, for example, implant studies. Today, in modern medicine the use of implants is considered standard practice. The past two decades of constant development has established the importance of implants in dentistry, orthopedics, as well as extended their applications to other areas such as aesthetic medicine. Fundamental to the success of implants is the knowledge of the biological processes involved in interactions between an implant and its host tissue, which are directly connected to the type of implant material and its surface properties. This review aims to demonstrate the broad applications of spectroscopic methods in implant material studies, particularly discussing hard implants, surface composition studies, and surface–cell interactions. Full article

(This article belongs to the Special Issue Practical Applications of Molecular Spectroscopy)

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