Proc. Of the 7th Asian Spectroscopy Conference (ASC 2020)最新文献

{"title":"Hydrogen bond dynamics of 9-fluorenone derivatives in water studied by two-dimensional infrared spectroscopy","authors":"Fujii Yuki, Ohta Kaoru, Tominaga Keisuke","doi":"10.32655/asc_8-10_dec2020.47","DOIUrl":"https://doi.org/10.32655/asc_8-10_dec2020.47","url":null,"abstract":"In solutions, a vibrational frequency of solute molecule is sensitive to changes of the solvent environment. Especially, in aqueous solution, hydrogen-bond making and breaking processes play an important role in the dynamics of water molecules surrounding the solute. For the past few decades, vibrational dynamics in aqueous solutions have been investigated by two-dimensional infrared (2D-IR) spectroscopy. 2D-IR spectroscopy is a powerful tool to obtain microscopic information in solution such as ultrafast solvent dynamics and local structure of solvent by probing the changes of vibrational frequency. In the present study, we performed 2D-IR spectroscopic measurements on 9-fluorenone-4-carboxylic acid (FL-4) and 9-fluorenone-2-carboxylic acid (FL-2, molecular structure is shown in Figure 1(a)) in aqueous solutions. By comparing the results of FL-4 and FL-2, we aim to find the relationship between molecular structure and vibrational dynamics. IR absorption D 2 the CO stretching mode is observed. The IR absorption spectra of FL-4 and FL-2 are reproduced by a single Gaussian function and a sum of two Gaussian functions, respectively. the analogy our we assigned the higher and lower bands in the IR spectrum of FL-2 to a complex of FL-2 and one D 2 O and a complex of FL-2 and two D 2 O, respectively. 2D-IR measurement provides information on the correlation of the vibrational spectrum at the pump frequency ( ω 1 ) and probe frequency ( ω 3 ). Figure 1(b) shows 2D-IR spectrum of FL-2 in D 2 O. The off-diagonal component at ( ω 1 , ω 3 ) = (1694 cm -1 , 1709 cm -1 ) may have information about the chemical exchange process occurring between the two hydrogen-bonded complexes. Therefore, we analyzed the 2D-IR spectra to obtain dynamical information of the hydrogen-bond making and breaking processes between the CO group and surrounding water molecules. Moreover, to obtain microscopic details of the system, we also conducted molecular dynamics (MD) simulation. By analyzing the trajectories obtained by MD simulation, we found that hydration structure around the CO group of FL-2 is largely different from that of FL-4. Consequently, the hydrogen bond dynamics between the CO group and water molecules differ between FL-2 and FL-4.","PeriodicalId":133438,"journal":{"name":"Proc. Of the 7th Asian Spectroscopy Conference (ASC 2020)","volume":"127 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121550018","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Plasmonic enhancement enabled by silver nanotriangles in Raman spectra of methylene blue","authors":"J. Haritha, Joshi Sarika, J. Arun, McNaughton Donald, S. Sumit, Chen Wenlong, R. W. Bayden, S. Shobha","doi":"10.32655/asc_8-10_dec2020.64","DOIUrl":"https://doi.org/10.32655/asc_8-10_dec2020.64","url":null,"abstract":"We present a method for detecting Methylene Blue (MB) using Confocal Raman Spectroscopy assisted with plasmonic enhancement from colloidal silver nanotriangles (NTs). The amplified Raman signal from the analyte aggregated over nanoclusters facilitated the detection of concentrations below 10-5 M. Methylene blue and silver NTs were mixed in equal proportions and a thin film of the solution was drop casted on a glass slide for collecting Raman data. Raman signals were acquired from the plasmonic hotspots (PHs) present in the sample, using 532 nm laser excitation. PHs in the sample were identified as dark blue spots, as seen under confocal microscope. These PHs were formed by the adsorption of dye on aggregated NTs and give a stronger signal because of localised surface plasmon resonance (LSPR). The triangular morphology contributed to a better enhancement due to the lighting rod effect [1]. From experimental data, it is inferred that the limit of detection was well below the concentration reached, 0.25x10-5 M. The main challenge to be addressed is the repeatability of the technique owing to the non-uniform and unstable hotspots scattered throughout the colloid. The reliability of this method can be increased with appropriate modification of the drop casting method to achieve a more uniform film. Considering the ease of implementation and cost-effectiveness, colloidal silver NTs are promising substrates in Surface Enhanced Raman Spectroscopy.","PeriodicalId":133438,"journal":{"name":"Proc. Of the 7th Asian Spectroscopy Conference (ASC 2020)","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133655845","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ultrafast charge transfer and recombination dynamics at the monolayer-multilayer WSe2 homojunction revealed by time-resolved photoemission electron microscopy","authors":"Xu Ce, S. B. Natalie, He Jinlu, Long Run, R. C. Alisson, Paradisanos Ioannis, K. O. Anna, Soavi Giancarlo, Tongay Sefaattin, C. Giulio, C. Andrea, V. P. Oleg, Loh Zhi-Heng","doi":"10.32655/asc_8-10_dec2020.67","DOIUrl":"https://doi.org/10.32655/asc_8-10_dec2020.67","url":null,"abstract":"Transition metal dichalcogenides (TMDs) have rapidly emerged as one of the most attractive families of two-dimensional materials due to their numerous outstanding electronic and optoelectronic properties. TMDs have layer-dependent band structures, exhibiting a dramatic transition from a direct bandgap in the monolayer (1L) to an indirect bandgap in the multilayer ( N L). TMD homojunctions form when a 1L TMD interfaces with an N L TMD of the same chemical composition. Such 1L/ N L TMD homojunctions are predicted to have similar properties as heterojunctions, which comprises two different TMDs. In this work, we employ time-resolved photoemission electron microscopy (TR-PEEM) to study the ultrafast carrier dynamics of a WSe 2 1L/ N L Type-I homojunction with high temporal (50 fs) and spatial (70 nm) resolution. Analysis of the TR-PEEM signal obtained from the individual components of the homojunction reveals timescales for carrier cooling and exciton-exciton annihilation. Beyond the carrier dynamics confined to the individual components of the homojunction, the TR-PEEM image also revealed the accumulation of holes at the interface of the homojunction; the width of the depletion zone is found to be 0.60 ± 0.17 µ m. Finally, TR-PEEM reveals electron-hole recombination across the homojunction with a time constant of 108 ± 9 ps. These results shed light on the ultrafast carrier dynamics of TMD homojunctions.","PeriodicalId":133438,"journal":{"name":"Proc. Of the 7th Asian Spectroscopy Conference (ASC 2020)","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122204219","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tracking ultrafast chemical reactions at the aqueous interface with femtosecond time-resolved HD-VSFG spectroscopy","authors":"Tahara Tahei","doi":"10.32655/asc_8-10_dec2020.24","DOIUrl":"https://doi.org/10.32655/asc_8-10_dec2020.24","url":null,"abstract":"There have been numbers of reports suggesting that chemical reactions at the water interfaces are different from the reactions in the bulk phase. However, it is very difficult to directly investigate chemical reactions at the water interfaces because of lack of suitable experimental methods. Heterodyne-detected vibrational sum frequency generation (HD-VSFG) spectroscopy is a powerful technique to study interfaces. Combined with the pump-probe method, HD-VSFG has been extended to time-resolved measurements, which opened a new door to investigate ultrafast dynamics at interfaces. HD-VSFG spectroscopy enables us to directly measure the spectrum of the second-order susceptibility () although conventional VSFG spectroscopy with homodyne detection can only provide the spectra of the absolute square of  (||). This advantage of HD-VSFG becomes even more critical in the time-resolved measurements which detect the pump-induced change of the spectra. In fact, homodyne time-resolved VSFG can provide the pump-induced change of || (||) but it is very difficult to interpret it. In contrast, time-resolved HD-VSFG directly gives  spectra and, in particular, the imaginary part of  (Im) can be directly compared to the timeresolved infrared and Raman spectra which correspond to Im and Im spectra, respectively. Fully utilizing this advantage of HD-VSFG, we developed UV-excited time-resolved HD-VSFG spectroscopy which enables tracking photochemical reactions and short-lived intermediates at aqueous interfaces. Very recently, we succeeded in tracking the photochemical reaction of phenol at the water interface. We observed several transients at the interface with femtosecond time resolution, and they were attributed to the reaction intermediates that also appear in the reaction in the solution phase. Surprisingly, however, it was found that dynamics at the interface is drastically accelerated, compared to the corresponding reaction in solution. We consider that this marked difference arises from the unique solvation structure around phenol at the interface, which significantly changes the relevant excited-state potential energy surface of phenol at the water interface. Largely different solvation environments at the interface is expected for all kinds of molecules, implying generality of the observation in our study, i.e., great difference in chemical reactions between the interface and the bulk.","PeriodicalId":133438,"journal":{"name":"Proc. Of the 7th Asian Spectroscopy Conference (ASC 2020)","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132832933","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Time-resolved experiment of IR-induced anion reaction dynamics","authors":"An Sejun, K. Dabin, Kim Sang Kyu","doi":"10.32655/asc_8-10_dec2020.57","DOIUrl":"https://doi.org/10.32655/asc_8-10_dec2020.57","url":null,"abstract":"A pump-probe experiment with the picosecond laser system was designed to reveal the vibrational mode-effect on the anion reaction dynamics. Vibrational excitation by IR pulse initiates the reaction of anions, such as autodetachment, electron-transfer, and isomerization. Visible pulse after IR pulse can detach the electron from the reaction product. Reaction rate, yield, energy, and isomer distribution can be obtained from the kinetic energy distribution of detached electron. Anion source, mass selection system, VMI photoelectron spectrometer, and high-intensity mid-IR [1] have been prepared for this IR-Vis pump-probe experiment. To overcome the low density of the ion packet and low absorption cross-section for the IR, we constructed the high-intensity (50~100 uJ) mid-IR optical setup for the picosecond laser system. Using the nonlinear property of the KTA crystal, we obtained mid-IR pulse (3000 ~ 5000 nm) from the difference frequency mixing between 791 nm and near-IR (950 ~ 1050 nm) pulses. 791 nm laser pulse was obtained from the 1 kHz picosecond amplifiers seeded by the Ti:sapphire oscillator. Near-IR pulse was generated from the optical parametric amplifier system pumped by 791nm pulse For the first target system, we planned the time-resolved photoelectron experiment for the nitromethane anion. Electrons can be autodetached by vibrational excitation [2] and we will measure autodetachment rate with our picosecond laser system. By comparing the autodetachment rate for each vibrational mode, we will be able to reveal the mechanism and vibrational mode effect on the autodetachment dynamics of ground state anion.","PeriodicalId":133438,"journal":{"name":"Proc. Of the 7th Asian Spectroscopy Conference (ASC 2020)","volume":"38 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132836561","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Charge transfer dynamics of 9-arylcarbazole studied by femtosecond transient absorption spectroscopy","authors":"Takamoto Kazuya, Ueno Yoshifumi, Ohta Kaoru, Akimoto Seiji, Matsubara Ryosuke, Tominaga Keisuke","doi":"10.32655/asc_8-10_dec2020.68","DOIUrl":"https://doi.org/10.32655/asc_8-10_dec2020.68","url":null,"abstract":"In chemistry it is important to understand reaction mechanisms in solutions at a molecular level because most chemical reactions occur in solutions. Intramolecular charge transfer (ICT) in solutions is one of the most basic reactions, and the reaction mechanism of ICT is influenced by not only solute-solvent interactions but also geometrical change of solute molecule. 3,6-Bis(dimethylamino)-9-(4-cyanophenyl)carbazole (BANCC, Figure 1(a)) consists of an electron donor of the carbazole unit and an acceptor of the cyanophenyl unit, which are connected by a single bond [1] . In order to elucidate the ICT reaction mechanism of BANCC, we performed real time observation of the reaction process in various organic solvents by femtosecond transient absorption (TA) spectroscopy. A pump pulse of 400 nm and a probe pulse of white light were generated from the output of a Ti:sapphire regenerative amplifier. The samples were excited at 400 nm under the magic angle condition, and transient spectra were recorded with femtosecond time resolution by multichannel detectors after dispersing the probe pulse by prisms. We also performed measurements on 3,6-bis(dimethylamino)carbazole (BAC, Figure 1(a)), a molecule of the electron donor part of BANCC. The absorption spectra of BANCC show two bands at 340 nm and 390 nm with no solvent dependence. These spectral features are the same as those of BAC. On the other hand, the fluorescence spectra of BANCC show a red shift as the solvent polarity increases, while those of BAC are less solvent-dependent. This result suggests that the excited state of BANCC is the ICT state with a large dipole moment. Figure 1(b) displays observed TA spectra of BANCC in dimethylsulfoxide (DMSO) following excitation at 400 nm. A band emerges at 680 nm immediately after photoexcitation, and a new band rises at 550 nm together with decay of the band at 680 nm. Because the band at 680 nm is similar to the observed TA spectra of BAC, it is considered that the carbazole unit is locally excited by photoexcitation followed by charge transfer to the cyanophenyl group. Furthermore, a peak of the band at 550 nm shows a blue shift with a time constant of ~3 ps, which is similar to the solvation time of DMSO. The time constants of the blue shift in other solvents also show values close to the solvation times of these solvents. This suggests that the static and dynamic properties of the solvent have an effect on the ICT reaction. In presentation, we show the spectral features of the TA spectra in detail and discuss the molecular mechanism of the ICT reaction.","PeriodicalId":133438,"journal":{"name":"Proc. Of the 7th Asian Spectroscopy Conference (ASC 2020)","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114656198","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"NIR “matchbox size” spectrometer can quantify and detect malaria infection in Plasmodium falciparum infected red blood cells","authors":"A. John, Kochan Kamila, H. Philip, R. W. Bayden","doi":"10.32655/asc_8-10_dec2020.51","DOIUrl":"https://doi.org/10.32655/asc_8-10_dec2020.51","url":null,"abstract":"New point-of-care diagnostic approaches for malaria that are highly sensitive, portable and affordable are urgently needed to meet the World Health Organization’s objective of reducing malaria cases and related life losses by at least 90% globally on or before 2030. 1 In this study, an ultra-cheap matchbox size near-infrared (NIR) spectrophotometer was used for the first time to detect and quantify malaria infection in vitro from isolated dried red blood cells using a fingerpick volume (15 µl) of blood, down to 0.0001% parasitemia. This technique relies on detecting distinct changes associated with the NIR spectroscopic signatures of both infected and control RBCs spectra. The approach requires minimal sample preparation that entails a centrifugation step to isolate the RBCs. The spectrum is acquired within 3 s thus can be transferred with Global Position Satellite coordinates for epidemiological surveillance. Prior to its application for malaria detection, we first characterized the major biomarkers associated with infected and uninfected red blood cells in the near infrared region including hemozoin, hemoglobin and lipids. We then applied Principal Component Analysis and achieved an excellent separation between the infected and uninfected RBCs. Using Partial Least Squares Regression Analysis, a Root Mean Square Error of Prediction of 0.446 and 0.001 for the PLS- R models were achieved. Thus, we introduce a high-throughput alternative to Polymerize Chain Reaction DNA amplification and rapid diagnostic antibody test strips that can be established using inexpensive substrates and an affordable, highly portable and low power instrument. Moreover, data can be uploaded via a smartphone and analysed online from anywhere in the world, highlighting the potential of this approach for field deployment in remote villages where road access can be problematic.","PeriodicalId":133438,"journal":{"name":"Proc. Of the 7th Asian Spectroscopy Conference (ASC 2020)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130782726","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ultrafast deep-ultraviolet spectroscopy of ionised liquid water","authors":"Ng Zi Xuan, P. Samuel, Loh Zhi-Heng","doi":"10.32655/asc_8-10_dec2020.70","DOIUrl":"https://doi.org/10.32655/asc_8-10_dec2020.70","url":null,"abstract":"The ionisation of liquid water is a phenomenon that accompanies high-energy radiation with biological systems and aqueous solutions. The study of this process is of fundamental importance to radiation biology and radiation chemistry. [1-3] Upon photoionisation, a water radical cation, H 2 O ●+ , is produced upon an ejection of an electron which subsequently relaxes into the localized hydrated electron, e hyd- . The H 2 O ●+ radical cation undergoes a proton transfer reaction to yield a hydroxyl radical, ● OH and a hydronium ion, H 3 O + . Previous studies have measured the timescale of decay of the H 2 O ●+ radical cation to be 46 fs. [4] To build on that discovery, this study focuses on detecting the formation time of the proton transfer product, the ● OH radical, by monitoring its deep-ultraviolet (DUV) absorption. Herein, this study presents the successful generation of ultrashort DUV pulses, and the ultrafast pump-probe spectroscopic measurements of the absorption of the ● OH radical. An upper bound of 100 fs for the time constant of the formation of the ● OH radical was obtained (Fig. 1). With evidence of the formation of the ● OH radical and the limitations identified, this study lays the foundation for investigating the formation and vibrational relaxation dynamics of the the proton transfer reaction .","PeriodicalId":133438,"journal":{"name":"Proc. Of the 7th Asian Spectroscopy Conference (ASC 2020)","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133344173","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Application of two-dimensional optical spectroscopy: from ultrafast spectral diffusion to Lewis basicity","authors":"Do Thanh Nhut, Sim Jamie Hung Ni, N. H. Long, Lu Yunpeng, Tan Howe-Siang","doi":"10.32655/asc_8-10_dec2020.48","DOIUrl":"https://doi.org/10.32655/asc_8-10_dec2020.48","url":null,"abstract":"Two-dimensional optical spectroscopy (2DOS) is the optical version of the well-established 2D-NMR technique, e.g., COSY. With time resolution in the femtosecond regime, 2DOS is widely used to resolve the ultrafast frequency modulation dynamics, such as spectral diffusion, in various vibrational [1-2] and electronic [3-4] systems. Chlorophylls (Chls) a and b are two main types of photosynthetic pigments responsible for the light-harvesting and energy regulation of green plants on Earth. Here, we employ 2DOS to track the time evolution of the 2D peakshape (Fig. 1) and resolve the ultrafast spectral diffusion dynamics of the Chl Q y transition in various organic solvents. The obtained results suggest that Chls exhibit three different relaxation dynamics with the timescales of sub-picosecond (sub-ps), several ps and tens to hundreds of ps. The correlation between spectral diffusion timescales and the solvents’ Lewis basicity, together with the support of ab initio time-dependent density functional theory (TDDFT) calculations indicates that we are probing directly the the dative bond the solvent’s lone pair and the electrophilic Mg 2+ center of Chls. bond the solvent Lewis basicity. a time-resolved molecular chemical property – Lewis basicity.","PeriodicalId":133438,"journal":{"name":"Proc. Of the 7th Asian Spectroscopy Conference (ASC 2020)","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133045797","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chromophore structure in a long-lived intermediate of heliorhodopsins : switching of a hydrogen bonding partner of protonated Schiff base","authors":"Urui Taito, Otomo Akihiro, Mizuno Misao, Kandori Hideki, Mizutani Yasuhisa","doi":"10.32655/asc_8-10_dec2020.62","DOIUrl":"https://doi.org/10.32655/asc_8-10_dec2020.62","url":null,"abstract":"Heliorhodopsin (HeR) is a novel class of retinal proteins discovered in 2018 [1]. HeR contains an all-trans-retinal as a chromophore, which is covalently bound to a lysine residue through a protonated Schiff base linkage. Although amino acid sequences of HeR are largely different from those of type1 rhodopsins, a family of HeR shares the seven-transmembrane helix motif. Photoexcitation of the all-trans-retinal chromophore results in isomerization to a 13-cis form. This isomerization initiates a photocycle involving a series of intermediates, which are similar to those observed for type-1 rhodopsins. HeR has a long-lived intermediate in its photocycle, which is named the O intermediate, suggesting that the function of HeR is light sensing. In order to understand the functional role of the O intermediate, we investigated the chromophore structure in two HeRs, HeR 48C12 and T. archaeon HeR, using time-resolved resonance Raman spectroscopy. We measured resonance Raman spectra of the O intermediate of the two HeRs in H2O and D2O (Figure 1). The observed spectra of the O intermediate of the both HeRs showed that the chromophore configuration is 13-cis and 15-anti and that the polyene chain around the Schiff base is distorted. A comparison of frequencies and bandwidths of the C=N stretch bands of the O intermediate in H2O and D2O solutions indicated that the Schiff base is protonated and hydrogenbonded to a water molecule. The latter feature is in contrast to that the hydrogen bond partner is amino acid residue in the unphotolyzed state [2]. Therefore, it is likely that the protein structure around the Schiff base is much altered in the transition from the O intermediate to the unphotolyzed state. This alternation may be a reason for the long lifetime of the O intermediate, which is essential to signal transduction.","PeriodicalId":133438,"journal":{"name":"Proc. Of the 7th Asian Spectroscopy Conference (ASC 2020)","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114545803","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}