Excited state absoiption

In addition, the atoms have large manifolds of excited states which are not present in the molecule. Thus the possibilities for energy absoiption is greater in the atoms, leading to deviations from the Bragg s rale. 

This section aims to explain the significance of the Maxwell-BoIt2mann distribution of molecules among energy levels and to provide some measure of the lifetime of the excited states of the energy levels in relation to emission and absoiption in the infrared region. 

For Rb, sphaeroides w.t. and M21 the absoiption changes are virtually temperature independent over the temperature range studied, hi fact between 100 K and 175 K the three preparations studied show no temperature dependence and yield very similar B896 excited state life times. The slightly faster value measured for M21 is probably due to mixing in of some B875 decay. 

A very widely employed method for the measurement of spin-orbit state-specific rate constants is the time-resolved measurement of the concentrations of individual atomic levels after formation of these species from a suitable precursor, either by flash photolysis [13], or, more recently, by laser photodissociation. The concentrations of the various atomic reactant states are monitored by atomic absorption or fluorescence spectroscopy using atomic emission sources [14], or, for spin-orbit-excited states, by observation of the spontaneous infrared emission [15-18]. Recently, Leone and co-workers have utilized gain/absoiption of a colour centre and diode infrared laser to probe the relative populations of ground and spin-orbit excited halogen atoms produced in a chemical reaction [19] and also by photodissociation [20],... 

Abs absoiption transitions of cytosine in water experimental data for keto-N3H and imino tautomers correspond to 3-methylcytosine and 3-methylcytidine, respectively, obtained in aqueous solution at pH 11 [279], °ground state dipole moments of keto-N3H, imino and enol tautomers at the HF/6-311G(d,p) level are 8.15, 5.12 and 3.34 Debye, respectively, scaled (scaling factor 0.72) excitation energies, Rydberg contamination. 

Intense visible absoiption bands with max = 590 nm e 87,000 mol" dm cm". Absoiption is pH dependent with the colour changing from purple through blue to yellow with decreasing pH. Shows very little fluorescence due to rapid non-radiative decay from the first excited singlet to the groimd state in a few ps [156]. 

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