Shifted excitation Raman difference spectroscopy: from diode lasers to in situ applications

2018 ◽  
Author(s):  
Martin Maiwald ◽  
Bernd Sumpf
Keyword(s):  
Diode Lasers ◽  
Difference Spectroscopy

In situ reflectance difference spectroscopy of N-plasma doped ZnTe grown by molecular beam epitaxy

1998 ◽  
Vol 73 (26) ◽  
pp. 3857-3859 ◽  
Author(s):  
D. Stifter ◽  
M. Schmid ◽  
K. Hingerl ◽  
A. Bonanni ◽  
M. Garcia-Rocha ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Difference Spectroscopy ◽  
Reflectance Difference Spectroscopy

Reflectance difference spectroscopy as an optical probe for the in situ determination of doping levels in GAAS

2006 ◽  
Author(s):  
A. Lastras-Martinez ◽  
I. Lara-Velazquez ◽  
R.e. Balderas-Navarro ◽  
J. Ortega-Gallegos ◽  
L.f. Lastras-Martinez
Keyword(s):  
Optical Probe ◽  
Difference Spectroscopy ◽  
Reflectance Difference Spectroscopy

scholarly journals 1 ML Wetting Layer upon Ga(As)Sb Quantum Dot (QD) Formation on GaAs Substrate Monitored with Reflectance Anisotropy Spectroscopy (RAS)

2018 ◽  
Vol 2018 ◽  
pp. 1-7
Author(s):  
Henning Fouckhardt ◽  
Johannes Strassner ◽  
Thomas H. Loeber ◽  
Christoph Doering
Keyword(s):  
Gaas Substrate ◽  
Semiconductor Quantum Dots ◽  
Ex Situ ◽  
Difference Spectroscopy ◽  
Wetting Layer ◽  
Reflectance Anisotropy ◽  
Atomic Force ◽  
Monitoring Technique ◽  
Scientific Dispute

III/V semiconductor quantum dots (QD) are in the focus of optoelectronics research for about 25 years now. Most of the work has been done on InAs QD on GaAs substrate. But, e.g., Ga(As)Sb (antimonide) QD on GaAs substrate/buffer have also gained attention for the last 12 years. There is a scientific dispute on whether there is a wetting layer before antimonide QD formation, as commonly expected for Stransky-Krastanov growth, or not. Usually ex situ photoluminescence (PL) and atomic force microscope (AFM) measurements are performed to resolve similar issues. In this contribution, we show that reflectance anisotropy/difference spectroscopy (RAS/RDS) can be used for the same purpose as an in situ, real-time monitoring technique. It can be employed not only to identify QD growth via a distinct RAS spectrum, but also to get information on the existence of a wetting layer and its thickness. The data suggest that for antimonide QD growth the wetting layer has a thickness of 1 ML (one monolayer) only.

scholarly journals How [FeFe]-Hydrogenase Facilitates Bidirectional Proton Transfer

2019 ◽  
Author(s):  
Moritz Senger ◽  
Viktor Eichmann ◽  
Konstantin Laun ◽  
Jifu Duan ◽  
Florian Wittkamp ◽  
...  
Keyword(s):  
Amino Acid ◽  
Proton Transfer ◽  
Active Site ◽  
Molecular Hydrogen ◽  
H2 Production ◽  
Amino Acid Residues ◽  
Difference Spectroscopy ◽  
Dynamic Changes ◽  
In Situ Ir

Hydrogenases are metalloenzymes that catalyse the interconversion of protons and molecular hydrogen, H2. [FeFe]-hydrogenases show particularly high rates of hydrogen turnover and have inspired numerous compounds for biomimetic H2 production. Two decades of research on the active site cofactor of [FeFe]-hydrogenases have put forward multiple models of the catalytic proceedings. In comparison, understanding of the catalytic proton transfer is poor. We were able to identify the amino acid residues forming a proton transfer pathway between active site cofactor and bulk solvent; however, the exact mechanism of catalytic proton transfer remained inconclusive. Here, we employ in situ IR difference spectroscopy on the [FeFe]-hydrogenase from Chlamydomonas reinhardtii evaluating dynamic changes in the hydrogen-bonding network upon catalytic proton transfer. Our analysis allows for a direct, molecular unique assignment to individual amino acid residues. We found that transient protonation changes of arginine and glutamic acid residues facilitate bidirectional proton transfer in [FeFe]-hydrogenases.<br>

In situ X-ray observations of pure-copper layer formation with blue direct diode lasers

2019 ◽  
Vol 480 ◽  
pp. 861-867 ◽  
Author(s):  
Yuji Sato ◽  
Masahiro Tsukamoto ◽  
Takahisa Shobu ◽  
Yoshinori Funada ◽  
Yorihiro Yamashita ◽  
...  
Keyword(s):  
Diode Lasers ◽  
Pure Copper ◽  
Copper Layer ◽  
Layer Formation ◽  
X Ray

In situ reflectance difference spectroscopy of p-type ZnTe:N grown by MBE

2000 ◽  
Vol 373 (1-2) ◽  
pp. 41-45 ◽  
Author(s):  
D Stifter ◽  
A Bonanni ◽  
M Garcı́a-Rocha ◽  
M Schmid ◽  
K Hingerl ◽  
...  
Keyword(s):  
Difference Spectroscopy ◽  
Reflectance Difference Spectroscopy ◽  
P Type
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