Influence of the Fermi Energy on Si–H Vibrational Modes in Amorphous and Microcrystalline Silicon

2000 ◽  
Vol 609 ◽  
Author(s):  
N. H. Nickel ◽  
P. Lengsfeld
Keyword(s):  
Raman Spectroscopy ◽  
Hydrogen Bonding ◽  
Structural Change ◽  
Fermi Energy ◽  
Structural Changes ◽  
Vibrational Modes ◽  
Microcrystalline Silicon ◽  
Additional Mode ◽  
Local Vibrational Modes

ABSTRACTThe influence of boron and phosphorous doping and the effect of structural changes on hydrogen bonding in a-Si:H and µc-Si are investigated using Raman spectroscopy. Information on H bonding is obtained from Si-H stretching local vibrational modes (LVM's). In n-type and undoped a-Si:H the LVM's of isolated Si-H near 2000 cm−1 and clustered Si-H around 2100 cm−1 can be clearly distinguished. In heavily B doped a-Si:H, however, the LVM at 2100 cm−1 disappears. A structural change from a-Si:H to µc-Si gives rise to an additional mode centered at 1911 cm−1. Similar LVM's are observed in poly-Si containing platelets.

scholarly journals Detection of local vibrational modes induced by intrinsic defects in undoped BaSi2 light absorber layers using Raman spectroscopy

2018 ◽  
Vol 124 (2) ◽  
pp. 025301 ◽  
Author(s):  
Takuma Sato ◽  
Hirofumi Hoshida ◽  
Ryota Takabe ◽  
Kaoru Toko ◽  
Yoshikazu Terai ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Vibrational Modes ◽  
Intrinsic Defects ◽  
Light Absorber ◽  
Local Vibrational Modes

The dependence of thymine and thymidine Raman spectra on solvent

2004 ◽  
Vol 82 (6) ◽  
pp. 1092-1101 ◽  
Author(s):  
L Beyere ◽  
P Arboleda ◽  
V Monga ◽  
G R Loppnow
Keyword(s):  
Raman Spectroscopy ◽  
Hydrogen Bonding ◽  
Raman Spectra ◽  
Vibrational Modes ◽  
Frequency Shifts ◽  
Hydrogen Bonding Interactions ◽  
Lone Pairs ◽  
Vibrational Bands ◽  
Donor Numbers ◽  
Solvent Molecules

Recent work has focused on developing Raman spectroscopy as a noninvasive probe of DNA interactions with solvents, intercalants, proteins, and other ligands. Here, we report the Raman spectra of thymine in eight solvents and thymidine in nine solvents obtained with visible excitation. Raman spectra under acidic, neutral, and basic conditions were also obtained of both thymine and thymidine. Changes in both the frequencies and intensities of several of the vibrational bands in the 800–1800 cm–1 region are observed. No evidence of deprotonation in the different solvents is observed for either thymine or thymidine. Correlations of the observed frequency shifts of specific vibrational modes with characteristic properties of the solvent for both thymine and thymidine show a significant correlation with acceptor and donor numbers, measures of the hydrogen-bonding ability of the solvent, in both thymine and thymidine. These results are interpreted in terms of hydrogen-bonding interactions between the N-H protons of the thymine base and lone pairs of electrons on the solvent molecules and between the solvent hydrogens and lone pairs on C=O sites. The solvent-dependent intensity in vibrational bands of thymine between 1500 and 1800 cm–1 indicates a strong interaction between thymine and solvent at the C=O and N-H sites that leads to separation of the C=O stretches from the C=C stretch. The intensity variations with solvent were much smaller for thymidine than for thymine, perhaps as a result of replacing the N1 proton by the sugar. These results suggest that Raman spectroscopy is uniquely sensitive to specific interactions of thymine and thymidine with their environment.Key words: Raman spectroscopy, thymine, thymidine, solvent effects, hydrogen bonding.

scholarly journals Optical Spectroscopy of a Nitrogen-Hydrogen Complex in ZnSe

1993 ◽  
Vol 325 ◽  
Author(s):  
J. A. Wolk ◽  
J. W. Ager ◽  
K. J. Duxstad ◽  
E. E. Haller ◽  
N. R. Taskar ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Vapor Phase ◽  
Vibrational Mode ◽  
Vibrational Modes ◽  
Organic Vapor ◽  
Infrared And Raman Spectroscopy ◽  
Metal Organic ◽  
Polarized Raman Spectroscopy ◽  
Local Vibrational Modes ◽  
Polarized Raman

AbstractWe have observed two local vibrational modes related to H bonded to N acceptors in ZnSe samples grown by metal organic vapor phase epitaxy. The modes have been seen in both infrared and Raman spectroscopy. The new mode seen at 3194 cm-1 is assigned to an N-H stretching vibrational mode and the mode found at 783 cm-1 is tentatively assigned to an N-H wagging vibrational mode. Polarized Raman spectroscopy was used to determine that the symmetry of the defect complex is C3v, which implies that the H atom is in either a bonding or anti-bonding position.

Transport Path in Hydrogenated Microcrystalline Silicon

2002 ◽  
Vol 715 ◽  
Author(s):  
N. Wyrsch ◽  
C. Droz ◽  
L. Feitknecht ◽  
J. Spitznagel ◽  
A. Shah
Keyword(s):  
Raman Spectroscopy ◽  
Volume Fraction ◽  
Conductivity Measurement ◽  
Dark Conductivity ◽  
Transition Regime ◽  
Conductivity Data ◽  
Crystalline Volume Fraction ◽  
Microcrystalline Silicon ◽  
Crystalline Fraction ◽  
Transport Path

AbstractUndoped microcrystalline silicon samples deposited in the transition regime between amorphous and microcrystalline growth have been investigated by dark conductivity measurement and Raman spectroscopy. From the latter, a semi-quantitative crystalline volume fraction Xc of the sample was deduced and correlated with dark conductivity data in order to reveal possible percolation controlled transport. No threshold was observed around the critical crystalline fraction value Xc of 33%, as reported previously, but a threshold in conductivity data was found at Xc≈50%. This threshold is interpreted here speculatively as being the result of postoxidation, and not constituting an actual percolation threshold.

Expression and Solution NMR Study of Multi-site Phosphomimetic Mutant BCL-2 Protein

2019 ◽  
Vol 26 (6) ◽  
pp. 449-457
Author(s):  
Ting Song ◽  
Keke Cao ◽  
Yu dan Fan ◽  
Zhichao Zhang ◽  
Zong W. Guo ◽  
...  
Keyword(s):  
Structural Change ◽  
Structural Biology ◽  
Quantum Coherence ◽  
Structural Changes ◽  
Solution Nmr ◽  
Flexible Loop ◽  
Loop Region ◽  
Loop Domain ◽  
Nmr Study ◽  
Binding Groove

Background: The significance of multi-site phosphorylation of BCL-2 protein in the flexible loop domain remains controversial, in part due to the lack of structural biology studies of phosphorylated BCL-2. Objective: The purpose of the study is to explore the phosphorylation induced structural changes of BCL-2 protein. Methods: We constructed a phosphomietic mutant BCL-2(62-206) (t69e, s70e and s87e) (EEEBCL- 2-EK (62-206)), in which the BH4 domain and the part of loop region was truncated (residues 2-61) to enable a backbone resonance assignment. The phosphorylation-induced structural change was visualized by overlapping a well dispersed 15N-1H heteronuclear single quantum coherence (HSQC) NMR spectroscopy between EEE-BCL-2-EK (62-206) and BCL-2. Results: The EEE-BCL-2-EK (62-206) protein reproduced the biochemical and cellular activity of the native phosphorylated BCL-2 (pBCL-2), which was distinct from non-phosphorylated BCL-2 (npBCL-2) protein. Some residues in BH3 binding groove occurred chemical shift in the EEEBCL- 2-EK (62-206) spectrum, indicating that the phosphorylation in the loop region induces a structural change of active site. Conclusion: The phosphorylation of BCL-2 induced structural change in BH3 binding groove.

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