Fluorescence decay of aromatic vapours. III. Single vibronic lifetimes and collision cross-sections for pyrimidine

1978 ◽  
Vol 31 (9) ◽  
pp. 1875 ◽  
Author(s):  
PR Nott ◽  
BK Selinger
Keyword(s):  
Small Molecule ◽  
Cross Sections ◽  
Pressure Dependence ◽  
Hard Sphere ◽  
Pressure Range ◽  
Fluorescence Decay ◽  
Decay Process ◽  
Intersystem Crossing ◽  
Collision Cross Sections ◽  
Effective Collision

In this paper the results of a lifetime study of the 1B1 state of pyrimidine vapour in the pressure range 1.2-60 Pa are presented. These lifetimes show an extraordinary pressure dependence, with collision cross-sections of 30-40 times hard sphere. It is shown that pyrimidine behaves as a small molecule. The collision-induced decay process is intersystem crossing and it is the most effective collision-induced process yet reported for the small-molecule limit.

Quantum mechanical calculations of effective collision cross-sections for He-N2interaction

1991 ◽  
Vol 72 (6) ◽  
pp. 1347-1364 ◽  
Author(s):  
Frederick R.W. McCourt ◽  
Velisa Vesovic ◽  
William A. Wakeham ◽  
Alan S. Dickinson ◽  
Merih Mustafa
Keyword(s):  
Cross Sections ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
Collision Cross Sections ◽  
Effective Collision

Pressure dependence of intersystem crossing in aromatic vapours

1971 ◽  
Vol 323 (1552) ◽  
pp. 11-28 ◽  
Keyword(s):  
Density Of States ◽  
Aromatic Hydrocarbons ◽  
Pressure Dependence ◽  
Vibrational Relaxation ◽  
Pressure Range ◽  
Vapour Phase ◽  
Fluorescence Yield ◽  
Gas Pressure ◽  
Intersystem Crossing ◽  
Low Pressures

The triplet yield of several aromatic hydrocarbons irradiated in the vapour phase decreases as the total gas pressure is decreased, approaching zero at zero pressure. Conversely, the fluorescence yield increases as the pressure is lowered. A theory of this pressure dependence is given which recognizes that intersystem crossing, which is normally irreversible owing to stabilization by vibrational relaxation, must become reversible at low pressures. To account for the experimental results over the whole pressure range it is also necessary to take into account the dependence of intersystem crossing rates on the density of states and therefore on the energy of excitation.

How useful is molecular modelling in combination with ion mobility mass spectrometry for ‘small molecule’ ion mobility collision cross-sections?

The Analyst ◽  
2015 ◽  
Vol 140 (20) ◽  
pp. 6814-6823 ◽  
Author(s):  
Cris Lapthorn ◽  
Frank S. Pullen ◽  
Babur Z. Chowdhry ◽  
Patricia Wright ◽  
George L. Perkins ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Cross Section ◽  
Small Molecule ◽  
Cross Sections ◽  
Ion Mobility ◽  
Molecular Modelling ◽  
Collision Cross Section ◽  
Ion Mobility Mass Spectrometry ◽  
Collision Cross Sections

Evaluation of N2(g) and He(g) MOBCAL collision cross section values from 20 compounds ∼ m/z 122 to 609.

Sign in / Sign up

Export Citation Format

Share Document