- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Variable-Temperature Resonance Raman Studies to Probe Interchain Ordering for Semiconducting Conjugated Polymers with Different Chain Curvature
摘要： The morphology and crystallinity of the polymers used to fabricate bulk heterojuction (BHJ) solar cells significantly influences the efficiency of the cells. We have used variable-temperature (VT) spectroscopy techniques, namely VT emission and VT resonance Raman spectroscopy (VT-RRS), to examine how the backbone linearity of a conducting polymer affects its electronic response to temperature and variations in solution behavior. We have studied two types of donor–acceptor polymers used in BHJ cells with differing backbone structures; they are poly-{5,6-bis(tetradecyloxy)-4-(thiophen-2-yl)benzo[c]-1,2,5-thiadiazole} (PTBT) which has a curved and poly-{5,6-bis(tetradecyloxy)-4-(thieno[3,2-b]-thiophen-2-yl)benzo[c]-1,2,5-thiadiazole} (PTTBT) which has a linear chain structure. Time-dependent density functional theory (TD-DFT) calculations and resonance Raman spectra (RRS) of PTTBT revealed the presence of three electronic transitions, with character that varies between p to p*, mixed p to p*/charge transfer and pure charge transfer in nature. Emission spectra of PTTBT showed spectral changes at 650 and 710 nm with varied temperature ((cid:2)10 to 60 8C). Variable-temperature RRS was measured in resonance with the lowest and highest energy electronic transitions. The changes were interpreted using two-dimensional correlation spectroscopy (2DCOS) analysis. PTTBT showed gradual shifts to lower wavenumbers of modes at around 1425, 1450 and 1500 cm(cid:2)1. For PTBT larger and more rapid spectral changes are observed at 1440 and 1460 cm(cid:2)1 consistent with greater variation in the electronic nature upon heating. Further study into the influence of polymer linearity on crystallinity and long range order was carried out using low-frequency Raman (LFR) to examine drop cast films under a variety of different conditions. LFR spectra showed that PTTBT has a band at 73 cm(cid:2)1. This is observed under a variety of film-forming conditions. PTBT does not show distinct low frequency modes, consistent with its low crystallinity.
关键词： resonance Raman spectroscopy,low-frequency Raman,long range order,variable temperature,conducting polymers
更新于2025-09-23 15:23:52
-
Rapid and sensitive surface-enhanced resonance Raman spectroscopy detection for norepinephrine in biofluids
摘要： Norepinephrine (NE) is a kind of catecholamine neurotransmitter that participates significant function in living organism. Rapid and sensitive detection target in complex system is crucial in analytical science. A facile ferric citrate (CA‐Fe (III)) sensor was designed successfully for sensitive detection of NE by surface‐enhanced resonance Raman spectroscopy (SERRS) method. This CA‐Fe (III) sensor was prepared by modifying Fe (III) on the surface of uniform Au nanoparticles (NPs) wrapped with citrate (CA) stabilizer. The implementation of NE selective detection is attributed to significant enhancement provided by Au NPs and additional enhancement provided by ligand‐to‐metal charge transfer between chromophore and analyte. In addition, a universal CH3OH, HCl, and petroleum ether added in sequence pretreatment method was developed and applied to purify and enrich the target in practical biological sample, realizing selective detection of NE in biofluids. This novel sensor combined with SERRS and pretreatment strategy not only amplifies the Raman signal of NE but also paves the way for pretreating sample in complex system.
关键词： norepinephrine,pretreatment method,ferric citrate sensor,surface‐enhanced resonance Raman spectroscopy,biofluids
更新于2025-09-23 15:21:01
-
Atypical Defect-Mediated Photoluminescence and Resonance Raman Spectroscopy of Monolayer WS2
摘要： Defects play an indispensable role in tuning the optical properties of two-dimensional(2D) materials. Herein, we study the influence of defects on the photoluminescence (PL) and resonance Raman spectra of as-grown monolayer(1L) WS2. Increasing the density of defects significantly lowers the excitonic binding energy by up to 110 meV. These defect-modified excitonic binding energies in1L-WS2 strongly mediate the Raman resonance condition, resulting in unexpected Raman intensity variations in the LA(M), 2LA(M) and phonon modes. The sample with the highest density of defects exhibits an almost temperature independent resonance in different Raman modes at low temperature, while the samples with low densities of defects exhibit clear resonance with decreasing temperature. This study will further increase our understanding of the role of defects in resonance Raman spectroscopy and of the phonon-exciton interaction in 1L-WS2.
关键词： photoluminescence,defects,excitonic binding energy,resonance Raman spectroscopy,monolayer WS2
更新于2025-09-19 17:15:36
-
AIP Conference Proceedings [AIP Publishing PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS: ICAM 2019 - Kerala, India (12–14 June 2019)] PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS: ICAM 2019 - Study of plasmonic effect in Cu2ZnSnS4-Ag nanocomposite thin film fabricated by vacuum thermal co-evaporation
摘要： CZTS-Ag nanocomposite thin films were fabricated by co-evaporating CZTS in the form of pellet and Ag powder as source materials simultaneously using vacuum thermal co-evaporator. The weight percentage of Ag to CZTS is increased from 2 to 4%. The as-prepared nanocomposite films were post annealed at 500 °C for 1 hour in a vacuum tubular furnace. The crystal structure of the as-prepared and annealed samples is analyzed by x-ray diffraction. Chemical structure of the prepared films is studied using confocal Raman spectroscopy with an excitation wavelength of 785 nm which depicts the mixed phase formation of SnS and CZTS. The observed blue shift in absorption edge in CZTS as well as broadened absorption in the entire visible region in Ag based CZTS nanocomposite could be due to the effect from Ag nanoparticles, verifying the strong existence of surface plasmon resonance in the visible region.
关键词： surface plasmon resonance,Raman spectroscopy,optical absorption,vacuum thermal co-evaporation,CZTS-Ag nanocomposite
更新于2025-09-12 10:27:22
-
Features of Vibrational and Electronic Structures of Decavanadate Revealed by Resonance Raman Spectroscopy and Density Functional Theory
摘要： Polyoxometalates are known to be inhibitors of a diverse collection of enzymes, although the specific interactions that lead to this bioactivity are still unclear. Spectroscopic characterization may be an invaluable if indirect tool for remedying this problem, yet this requires clear, cogent assignment of polyoxometalate spectra before the complicating effect of their binding to large biomolecules can be considered. We report the use of FT-IR and resonance Raman spectroscopies alongside density functional theory to describe the vibrational and electronic structures of decavanadate, [V10O28]6–. Our computational model, which reproduced the majority of vibrational features to within 10 cm–1, was then used to identify an axial oxo ligand as the most likely position of the acidic proton in the related cluster [HV10O28]5–. As resonance Raman spectroscopy can directly interrogate chromophores embedded in complex systems, this approach may be of general use in answering structural questions about polyoxometalate-enzyme systems.
关键词： vibrational and electronic structures,Polyoxometalates,decavanadate,density functional theory,resonance Raman spectroscopy
更新于2025-09-12 10:27:22
-
Laser induced fano scattering, electron- phonon coupling, bond length and phonon life time of α-Fe2O3 nanostructure
摘要： We have extensively studied the laser-induced Fano scattering, electron- phonon coupling, bond length and phonon lifetime of α-Fe2O3 nanostructure prepared through simple co-precipitation method. A noticeable red shift and an asymmetry have been observed in the phonon modes of the prepared α-Fe2O3 nanostructure. The traditional assessment of asymmetric broadening and a red shift in the Raman spectra of nanomaterial was due to the quantum confinement effect. In the present investigation, the red shift and the asymmetry in phonon modes of α-Fe2O3 nanostructure have been studied on the basis of its heating effect and Fano interference between the discrete phonon and the laser-induced electron plasma in the nanomaterial. The observed asymmetrical factors of A1g(1) and Eg(4) phonon modes were positive and negative respectively and is seen to be decreasing with laser power. Laser-induced surface temperature of the material have been studied using the Stokes/anti-Stokes method. Bond lengths of the Fe-O molecules present in the α-Fe2O3 nanomaterial were increased and the calculated Fr?hlich interactions were decreased with laser energy.
关键词： heating effect,Surface temperature,Fano resonance,Raman spectroscopy,Bond length.
更新于2025-09-12 10:27:22