Direct comparison of phase-sensitive vibrational sum frequency generation with maximum entropy method: Case study of water

2011 ◽  
Vol 135 (22) ◽  
pp. 224701 ◽  
Author(s):  
Alex G. F. de Beer ◽  
Jean-Sebastièn Samson ◽  
Wei Hua ◽  
Zishuai Huang ◽  
Xiangke Chen ◽  
...  
Keyword(s):  
Maximum Entropy ◽  
Maximum Entropy Method ◽  
Entropy Method ◽  
Sum Frequency Generation ◽  
Sum Frequency ◽  
Phase Sensitive ◽  
Frequency Generation

scholarly journals Mapping Molecular Orientation with Phase Sensitive Vibrationally Resonant Sum-Frequency Generation Microscopy

2013 ◽  
Vol 117 (20) ◽  
pp. 6149-6156 ◽  
Author(s):  
Yang Han ◽  
Varun Raghunathan ◽  
Ran-ran Feng ◽  
Hiroaki Maekawa ◽  
Chao-Yu Chung ◽  
...  
Keyword(s):  
Molecular Orientation ◽  
Sum Frequency Generation ◽  
Sum Frequency ◽  
Phase Sensitive ◽  
Frequency Generation

scholarly journals High-resolution phase-sensitive sum frequency generation spectroscopy by time-domain ptychography

2020 ◽  
Vol 45 (21) ◽  
pp. 6082
Author(s):  
Tobias Schweizer ◽  
Bruno G. Nicolau ◽  
Priscila Cavassin ◽  
Thomas Feurer ◽  
Natalie Banerji ◽  
...  
Keyword(s):  
High Resolution ◽  
Time Domain ◽  
Sum Frequency Generation ◽  
Sum Frequency ◽  
Sum Frequency Generation Spectroscopy ◽  
Phase Sensitive ◽  
Frequency Generation

Electron densities by the maximum entropy method (MEM) for various types of prior densities: a case study on three amino acids and a tripeptide

2013 ◽  
Vol 69 (2) ◽  
pp. 203-213 ◽  
Author(s):  
Siriyara Jagannatha Prathapa ◽  
Swastik Mondal ◽  
Sander van Smaalen
Keyword(s):  
Maximum Entropy ◽  
Dynamic Model ◽  
Maximum Entropy Method ◽  
Entropy Method ◽  
Topological Descriptors ◽  
Acta Cryst ◽  
Density Maps ◽  
Large Spread ◽  
Better Than

Dynamic model densities according to Mondalet al.[(2012),Acta Cryst.A68, 568–581] are presented for independent atom models (IAM), IAMs after high-order refinements (IAM-HO), invariom (INV) models and multipole (MP) models of α-glycine, DL-serine, L-alanine and Ala–Tyr–Ala atT≃ 20 K. Each dynamic model density is used as prior in the calculation of electron density according to the maximum entropy method (MEM). We show that at the bond-critical points (BCPs) of covalent C—C and C—N bonds the IAM-HO and INV priors produce reliable MEM density maps, including reliable values for the density and its Laplacian. The agreement between these MEM density maps and dynamic MP density maps is less good for polar C—O bonds, which is explained by the large spread of values of topological descriptors of C—O bonds in static MP densities. The density and Laplacian at BCPs of hydrogen bonds have similar values in MEM density maps obtained with all four kinds of prior densities. This feature is related to the smaller spatial variation of the densities in these regions, as expressed by small magnitudes of the Laplacians and the densities. It is concluded that the use of the IAM-HO prior instead of the IAM prior leads to improved MEM density maps. This observation shows interesting parallels to MP refinements, where the use of the IAM-HO as an initial model is the accepted procedure for solving MP parameters. A deconvolution of thermal motion and static density that is better than the deconvolution of the IAM appears to be necessary in order to arrive at the best MP models as well as at the best MEM densities.

Progress in phase-sensitive sum frequency generation spectroscopy

2021 ◽  
Author(s):  
Shoichi Yamaguchi ◽  
Takuhiro Otosu
Keyword(s):  
Molecular Level ◽  
Sum Frequency Generation ◽  
Sum Frequency ◽  
Surfaces And Interfaces ◽  
Sum Frequency Generation Spectroscopy ◽  
Phase Sensitive ◽  
Frequency Generation

Sum frequency generation (SFG) spectroscopy is a unique and powerful tool for investigating surfaces and interfaces at the molecular level. Phase-sensitive SFG (PS-SFG) is an upgraded technique that can overcome...

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