Dual frequency-comb spectroscopy of chromophores in condensed phases

Kim, JunWoo,Jeon, Jonggu,Yoon, Tai Hyun,Cho, Minhaeng Elsevier Science Publishers [etc.] 2019 Chemical Physics Vol. No.

<P><B>Abstract</B></P> <P>Femtosecond time-resolved spectroscopy and frequency-comb spectroscopy have been individually developed to achieve better time and frequency resolutions, respectively. The two spectroscopic techniques have been developed for different systems, even though they use mode-locked laser in common. Recently, there was an interesting merge of the two techniques into a dual frequency-comb (DFC) spectroscopy, resulting in a new femtosecond spectroscopy with simple instrumentation and high data acquisition speed compared to conventional femtosecond spectroscopic techniques. By slightly detuning the repetition rates of two phase-locked frequency-comb lasers, both automatic time-delay scanning and parallel data recording with single point detectors are possible. Thus, we anticipate that the DFC spectroscopy would allow one to expand the application limits of the conventional femtosecond spectroscopic methods. In this Perspective article, we provide reviews of linear and nonlinear DFC spectroscopy theory and applications with a perspective on the development of coherent multidimensional frequency-comb spectroscopy.</P>

분광학의 새로운 시장: MIT 분광학 학술대회(1933-1942)와 응용분광학의 발전

박민아 한국과학사학회 2007 한국과학사학회지 Vol.29 No.1

The annual conferences at MIT on spectroscopy and its applications provided a market where consumers and producers of spectrum analysis of substances could meet and exchange their knowledge, skills, and products on spectrum analysis. In ten conferences between 1933 and 1942, George Russell Harrison, the first director of the MIT Spectroscopy Laboratory and the organizer of the conferences, emphasized the application of spectroscopy to diverse fields of sciences and to practical problems in industries. Accordingly, conferences attracted not only physicists and astronomers who traditionally made uses of spectroscopes as research tools, but also biologists, medical doctors and research workers in government agencies and industries who were rather new-comers in the field. The close examination of conferences will show that the conferences stimulated self-awareness of applied spectroscopy as a specialized field and applied spectroscopists as a group.Then, why did these conferences emphasize applications of spectroscopy? I will show three factors influenced on Harrison’s emphasis on application: declining interests in atomic spectroscopy in the early 1930s; the Great Depression society which blamed science for its economic difficulty and unemployment; the 1930s’ MIT where application and cross-disciplinary research were encouraged.

Characterization of products from Fe(CO)₅ seeded CO diffusion flame

Kim, Kibum,Kim, Hae Kwang Pergamon Press 2018 Energy Vol.148 No.-

<P><B>Abstract</B></P> <P>Although Iron Pentacarbonyl (Fe(CO)<SUB>5</SUB>), one of common metallic additives has been applied to soot emission suppression in a few decades, the correct mechanism on soot reduction is not well-understood and still far controversial. Particular species presented in the flame could provide valuable information on the mechanisms of chemical reactions. With the fact in mind, the state of the fuel additive was identified using a variety of laser-based diagnostics and spectroscopic methods such as <I>in situ</I> Raman spectroscopy, laser-induced fluorescence (LIF), laser-induced breakdown spectroscopy, absorption spectroscopy, and X-ray photoelectron spectroscopy. Preliminary sets of experiments were conducted with Fe(CO)<SUB>5</SUB> seeded CO diffusion flame for eliminating the external environment interferences and variations due to soot particles that are normally produced from hydrocarbon fuel combustion. Any specific form of iron oxide was hardly detected while strong Fe signal was observed with <I>in sit</I>u analyses. The analytical results indicate that elemental Fe play crucial role as heterogeneous catalyst on carbon oxidation in any carbon-based fuel diffusion flame.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The dominant iron species obtained from Fe(CO)<SUB>5</SUB> seeded CO flame was elemental Fe. </LI> <LI> The formation of iron oxide was not observed using <I>in situ</I> Raman spectroscopy. </LI> <LI> Fe atomic emissions were observed using Fe LIF spectroscopy. </LI> <LI> No FeO florescence signal was detected. </LI> <LI> Fe absorption spectroscopy supported that elemental Fe are the major species. </LI> </UL> </P>

IR Correlation Spectroscopy using Microgratings to be Compared with Dispersive IR Spectroscopy#

신권수,조충만,최은우,김성규,김인철,박도현,강영일 대한화학회 2015 Bulletin of the Korean Chemical Society Vol.36 No.3

Microgratings that were designed and fabricated to generate IR absorption spectra of SF6 and NH3 on diffraction into a specific detection angle were tested by correlation spectroscopy. The micrograting diffraction provides a reference spectrum for a target molecule, and its cross-correlation with the transmission spectrum of a gas cell is obtained by varying the diffraction angle. As our optical setup can measure the dispersive transmission spectrum and the correlation spectrum under the same conditions, the two kinds of spectra were compared directly in terms of signal-to-noise ratio (SNR). The SNR’s of the correlation spectra were a few times lower than those of the dispersed spectra; therefore, the correlation spectroscopy can hardly be placed above the dispersive spectroscopy with respect to the SNR. The merit of the correlation spectroscopy is that a rather small range of modulation wavelength is needed to identify the target. Therefore, the correlation spectroscopy would be more useful for such target molecules whose spectra consist of broad peaks spread throughout a wide wavelength range.

Comparative nondestructive measurement of corn seed viability using Fourier transform near-infrared (FT-NIR) and Raman spectroscopy

Ambrose, A.,Lohumi, S.,Lee, W.H.,Cho, B.K. Elsevier Sequoia 2016 Sensors and actuators. B Chemical Vol.224 No.-

The commercialization of agriculture has driven the need to ascertain the quality of agricultural inputs, especially seeds in order to optimize output and increase economic returns. Seed viability is a critical consideration for ensuring a reasonably high harvest. More often than not, farmers experience losses after a significant percentage of seeds fail to germinate after planting. The loss of seed viability may be due to a number of reasons such as overheating during drying, physical damage during post-harvest processing, and ageing during storage. It is therefore critical for seed companies to sufficiently inspect their products and uphold them to acceptable seed quality standards in order to gain credibility and ensure business sustainability. In this study, the Fourier transform near-infrared (FT-NIR) and Raman spectroscopy techniques were used for evaluating seed viability to investigate their comparative advantages with regard to the corn viability test and classification. The techniques were applied to white, yellow, and purple corns with 300 samples in each category. The 300 sample corn seeds were divided into two groups of 150 seeds each; one group was heat-treated using microwaving, and the other was used as the control. Sample spectra from treated and untreated corn seeds were collected using an FT-NIR spectrometer in the wave range of 1000-2500nm, and then Raman spectrometer in the wave range of 170-3200cm<SUP>-1</SUP>. The collected spectra were divided into training and testing sets, corresponding to 70% and 30% of the total, respectively for calibration and validation of the techniques. Principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) were used to assess the spectral data from FT-NIR and Raman spectroscopy. The analysis results indicated that FT-NIR spectroscopy correctly classified viable and nonviable seeds for all the three categories of corns with a high accuracy of 100% and a predictive ability of more than 95%. Moreover, Raman spectroscopy demonstrated reasonably high classification accuracy with PLS-DA, but a significant number of seeds were overlapping when using PCA. In addition, an analysis of variance (ANOVA) indicated that the difference between treated and untreated corn seeds was not statistically significant (P<0.05). The study demonstrated that FT-NIR spectroscopy is superior to Raman spectroscopy in evaluating corn seed viability.

An in vitro evaluation of graphene oxide reduced by <i>Ganoderma</i> spp. in human breast cancer cells (MDA-MB-231)

Gurunathan, Sangiliyandi,Han, JaeWoong,Park, Jung Hyun,Kim, Jin Hoi Dove Medical Press 2014 INTERNATIONAL JOURNAL OF NANOMEDICINE Vol.9 No.-

<P><B>Background</B></P><P>Recently, graphene and graphene-related materials have attracted much attention due their unique properties, such as their physical, chemical, and biocompatibility properties. This study aimed to determine the cytotoxic effects of graphene oxide (GO) that is reduced biologically using <I>Ganoderma</I> spp. mushroom extracts in MDA-MB-231 human breast cancer cells.</P><P><B>Methods</B></P><P>Herein, we describe a facile and green method for the reduction of GO using extracts of <I>Ganoderma</I> spp. as a reducing agent. GO was reduced without any hazardous chemicals in an aqueous solution, and the reduced GO was characterized using a range of analytical procedures. The <I>Ganoderma</I> extract (GE)-reduced GO (GE-rGO) was characterized by ultraviolet-visible absorption spectroscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, dynamic light scattering, scanning electron microscopy, Raman spectroscopy, and atomic force microscopy. Furthermore, the toxicity of GE-rGO was evaluated using a sequence of assays such as cell viability, lactate dehydrogenase leakage, and reactive oxygen species generation in human breast cancer cells (MDA-MB-231).</P><P><B>Results</B></P><P>The preliminary characterization of reduction of GO was confirmed by the red-shifting of the absorption peak for GE-rGO to 265 nm from 230 nm. The size of GO and GE-rGO was found to be 1,880 and 3,200 nm, respectively. X-ray diffraction results confirmed that reduction processes of GO and the processes of removing intercalated water molecules and the oxide groups. The surface functionalities and chemical natures of GO and GE-rGO were confirmed using Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy. The surface morphologies of the synthesized graphene were analyzed using high-resolution scanning electron microscopy. Raman spectroscopy revealed single- and multilayer properties of GE-rGO. Atomic force microscopy images provided evidence for the formation of graphene. Furthermore, the effect of GO and GE-rGO was examined using a series of assays, such as cell viability, membrane integrity, and reactive oxygen species generation, which are key molecules involved in apoptosis. The results obtained from cell viability and lactate dehydrogenase assay suggest that GO and GE-rGO cause dose-dependent toxicity in the cells. Interestingly, it was found that biologically derived GE-rGO is more toxic to cancer cells than GO.</P><P><B>Conclusion</B></P><P>We describe a simple, green, nontoxic, and cost-effective approach to producing graphene using mushroom extract as a reducing and stabilizing agent. The proposed method could enable synthesis of graphene with potential biological and biomedical applications such as in cancer and angiogenic disorders. To our knowledge, this is the first report using mushroom extract as a reducing agent for the synthesis of graphene. Mushroom extract can be used as a biocatalyst for the production of graphene.</P>

Coating gold nanoparticles to a glass substrate by spin-coat method as a surface-enhanced raman spectroscopy (SERS) plasmonic sensor to detect molecular vibrations of bisphenol-a (BPA)

Eskandari, Vahid,Hadi, Amin,Sahbafar, Hossein Techno-Press 2022 Advances in nano research Vol.13 No.5

Bisphenol A (BPA) is one of the chemicals used in monomer epoxy resins and polycarbonate plastics. The surface-enhanced Raman spectroscopy (SERS) method is precise for identifying biological materials and chemicals at considerably low concentrations. In the present article, the substrates coated with gold nanoparticles have been studied to identify BPA and control the diseases caused by this chemical. Gold nanoparticles were made by a simple chemical method and by applying gold salt and trisodium citrate dihydrate reductant and were coated on glass substrates by a spin-coat approach. Finally, using these SERS substrates as plasmonic sensors and Raman spectroscopy, the Raman signal enhancement of molecular vibrations of BPA was investigated. Then, the molecular vibrations of BPA in some consumer goods were identified by applying SERS substrates as plasmonic sensors and Raman spectroscopy. The fabricated gold nanoparticles are spherical and quasi-spherical nanoparticles that confirm the formation of gold nanoparticles by observing the plasmon resonance peak at 517 nm. Active SERS substrates have been coated with nanoparticles, which improve the Raman signal. The enhancement of the Raman signal is due to the resonance of the surface plasmons of the nanoparticles. Active SERS substrates, gold nanoparticles deposited on a glass substrate, were fabricated for the detection of BPA; a detection limit of 10-9 M and a relative standard deviation (RSD) equal to 4.17% were obtained for ten repeated measurements in the concentration of 10-9 M. Hence, the Raman results indicate that the active SERS substrates, gold nanoparticles for the detection of BPA along with the developed methods, show promising results for SERS-based studies and can lead to the development of microsensors. In Raman spectroscopy, SERS active substrate coated with gold nanoparticles are of interest, which is larger than gold particles due to the resonance of the surface plasmons of gold nanoparticles and the scattering of light from gold particles since the Raman signal amplifies the molecular vibrations of BPA. By decreasing the concentration of BPA deposited on the active SERS substrates, the Raman signal is also weakened due to the reduction of molecular vibrations. By increasing the surface roughness of the active SERS substrates, the Raman signal can be enhanced due to increased light scattering from rough centers, which are the same as the larger particles created throughout the deposition by the spin-coat method, and as a result, they enhance the signal by increasing the scattering of light. Then, the molecular vibrations of BPA were identified in some consumer goods by SERS substrates as plasmonic sensors and Raman spectroscopy.

<i>Ginkgo biloba</i> : a natural reducing agent for the synthesis of cytocompatible graphene

Gurunathan, Sangiliyandi,Han, Jae Woong,Park, Jung Hyun,Eppakayala, Vasuki,Kim, Jin-Hoi Dove Medical Press 2014 INTERNATIONAL JOURNAL OF NANOMEDICINE Vol.9 No.-

<P><B>Background</B></P><P>Graphene is a novel two-dimensional planar nanocomposite material consisting of rings of carbon atoms with a hexagonal lattice structure. Graphene exhibits unique physical, chemical, mechanical, electrical, elasticity, and cytocompatible properties that lead to many potential biomedical applications. Nevertheless, the water-insoluble property of graphene restricts its application in various aspects of biomedical fields. Therefore, the objective of this work was to find a novel biological approach for an efficient method to synthesize water-soluble and cytocompatible graphene using <I>Ginkgo biloba</I> extract (GbE) as a reducing and stabilizing agent. In addition, we investigated the biocompatibility effects of graphene in MDA-MB-231 human breast cancer cells.</P><P><B>Materials and methods</B></P><P>Synthesized graphene oxide (GO) and GbE-reduced GO (Gb-rGO) were characterized using various sequences of techniques: ultraviolet-visible (UV-vis) spectroscopy, Fourier-transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and Raman spectroscopy. Biocompatibility of GO and Gb-rGO was assessed in human breast cancer cells using a series of assays, including cell viability, apoptosis, and alkaline phosphatase (ALP) activity.</P><P><B>Results</B></P><P>The successful synthesis of graphene was confirmed by UV-vis spectroscopy and FTIR. DLS analysis was performed to determine the average size of GO and Gb-rGO. X-ray diffraction studies confirmed the crystalline nature of graphene. SEM was used to investigate the surface morphologies of GO and Gb-rGO. AFM was employed to investigate the morphologies of prepared graphene and the height profile of GO and Gb-rGO. The formation of defects in Gb-rGO was confirmed by Raman spectroscopy. The biocompatibility of the prepared GO and Gb-rGO was investigated using a water-soluble tetrazolium 8 assay on human breast cancer cells. GO exhibited a dose-dependent toxicity, whereas Gb-rGO-treated cells showed significant biocompatibility and increased ALP activity compared to GO.</P><P><B>Conclusion</B></P><P>In this work, a nontoxic natural reducing agent of GbE was used to prepare soluble graphene. The as-prepared Gb-rGO showed significant biocompatibility with human cancer cells. This simple, cost-effective, and green procedure offers an alternative route for large-scale production of rGO, and could be used for various biomedical applications, such as tissue engineering, drug delivery, biosensing, and molecular imaging.</P>

MR Spectroscopy of Cerebral Fat Embolism in Cats

Park, Byung-Rae 대한의생명과학회 2005 Biomedical Science Letters Vol.11 No.2

To investigate the spectroscopic Eindings of embolized lesions induced with a fat-emulsion technique with magnetic resonance images (MRI). A fat emulsion was made with 0.1 m1 of triolein and 20 ml of normal saline. In 12 cats, the internal carotid artery was infused with the fat emulsion. Contrast-enhanced T1-weighted MRI and multivoxel spectroscopy were obtained at 1 hour, 1 and 4 days, and 1 week after embolization. NAA (N-acetylaspartate), Cr(creatine) and Cho(choline) were evaluated on the spectroscopy. Statitistical analysis wsperformed at the embolized and contralateral normal hemisphere in the integral and amplitude of NAA, Cr and Nho in time course. Also NAA/Cr and Cho/Cr were compared in both hemisphere and in time course. The embolized lesions showed contrast enhance ments on Gd-enhanced T1-weighted images at 1 hour. This contrast enhancement was decreased at day 1, and id not appear agter day 4. In spectroscopy, the embolized hemisphere showed no statistical difference to the normal contralateral side at 1 hour and in time course. NAA/Cr and Cho/Cr were not significantly different in both hemispheres at 1 hour and in time course. Cerebral-fat embolism induced by a triolein emulsion in cats revealed no statistical difference an MR spectroscopy. Triolein-emulsion can be used in the study of blood-brain barrier.

Consideration of Temperature and Slip Correction for Photothermal Spectrometry

이정훈 한국대기환경학회 2015 Asian Journal of Atmospheric Environment (AJAE) Vol.9 No.1

Temperature was considered to estimate the minimumdetectable absorption coefficient of aerosol particlesfrom photothermal spectroscopy. Light energyabsorbed by subsequent emission from the aerosolresults in the heating of the aerosol sample and consequentlycauses a temperature change as well aschanges in thermodynamic parameters of the sample. This thermal effect is the basis of photothermal spectroscopy. Photothermal spectroscopy has several typesof techniques depending on how the photothermaleffects are detected. Photothermal interferometrytraces the photothermal effect, refractive index, usingan interferometer. Photoacoustic spectroscopy detectsthe photothermal effect, sound wave, using amicrophone. In this study, it is suggested that thedetection limit for photothermal spectroscopy can beinfluenced by the introduction of a slip correction factorwhen the light absorption is determined in a hightemperature environment. The minimum detectableabsorption coefficient depends on the density, thespecific heat and the temperature, which are thermodynamicproperties. Without considering the slipcorrection, when the temperature of the environmentis 400 K, the minimum detectable absorption coefficientfor photothermal interferometry increases approximately0.3% compared to the case of 300 K. The minimum detectable absorption coefficient forphotoacoustic spectroscopy decreases only 0.2%compared to the case of 300 K. Photothermal interferometrydiffers only 0.5% point from photoacousticspectroscopy. Thus, it is believed that photothermalinterferometry is reliably comparable to photoacousticspectroscopy under 400 K.