The semiempirical molecular orbital calculation on [NiCl6]4− cluster. II. The choice of metal basis and models of population analysis

1972 ◽  
Vol 22 (12) ◽  
pp. 1232-1239 ◽  
Author(s):  
K. Polák ◽  
J. Málek
Keyword(s):  
Molecular Orbital ◽  
Population Analysis ◽  
Molecular Orbital Calculation ◽  
Metal Basis ◽  
Semiempirical Molecular Orbital

Photosensitized Reaction of Poly(L-lactic Acid) via Two-Photon Ionization of Dopant

2001 ◽  
Vol 708 ◽  
Author(s):  
Wataru Sakai ◽  
Kosuke Wakabayashi ◽  
Hiroshi Nishinaka ◽  
Hiroki Kawamoto ◽  
Motoi Kinoshita ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Molecular Orbital ◽  
Radical Cation ◽  
Main Chain ◽  
Molecular Orbital Calculation ◽  
Broad Absorption Band ◽  
Two Photon ◽  
Esr Spectrum ◽  
Photon Ionization ◽  
Semiempirical Molecular Orbital

ABSTRACTWe here studied photosensitized radical reaction of poly(L-lactic acid) (PLA) using spectrophotometry, electron spin resonance (ESR), gel permeation chromatography (GPC) measurements, and semiempirical molecular orbital calculation. PLA doped with N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) was irradiated at 77 K using UV light. After the irradiation, we observed a new broad absorption band that is assigned to TMPD radical cation produced by two-photon ionization. ESR spectrum of the irradiated sample also indicated presence of main chain scission radical of PLA as well as the TMPD radical cation. By increasing the irradiation time, the ESR spectrum changed by another radical species which is produced by dehydrogenation of PLA main chain. Spectral simulation for the obtained ESR spectra revealed changes of relative amounts. The GPC measurements clearly indicated decrease in molecular weight of PLA after the irradiation. The semiempirical molecular orbital calculation was used to confirm the reaction scheme of radical anion decomposition.

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