Excimer-exciplex profile

Rate constants are obtained from fluorescence decay analyses of the monomer decay profile I (t) and the excimer/exciplex profile Ig(t). These are fit to sums and differences of two exponential... 

As an example, scheme i) gives a new transient Raman spectrum in which all the observed vibrational bands have the same rise time and the same enhancement profile. In scheme ii) all the new bands should have the same rise time but the relative band intensity of the new spectrum should change upon changing the probe laser frequency (if B and C have different optical absorption profiles.). Scheme iii) predicts changes in the relative intensity of the new bands with both the laser probe frequency as well as the time of delay between the photolysis and probe laser pulses. The difference between scheme iii) and iv) is that in iii) the bands of C and D could have different rise and decay times while in iv) they all should have similar rise times. Schemes iii) and v) are similar except that A in iii) disappears permanently upon laser exposure while in v) A regains its concentration and no permanent photochemical damage takes place. In scheme vi) the rise time of the vibrational bands of the (AB) transient (an excimer or an exciplex) should depend on the concentration of B. 

Figure 13.12 shows the UV absorption profile of typical gases found (O2, H2O) and formed (O3) in the ambient environment of exposure tools. The Schumann-Runge band (180-210-nm) and continuum (<180-nm) regions dominate the photochemistry of molecular oxygen around 193 nm (of ArF exciplex laser) and 157 nm (of F2 excimer laser), respectively. 

Organic exciplexes are best identified by studying the variation of their emission spectra with concentration. This is illustrated in Figure 19 for pyrene (py). At low pyrene concentrations (<10 M), the major luminescence band is due to the monomer. The characteristics of the monomer emission include (i) vibronic structure is present, and (ii) the emission profile is independent of concentration at concentrations <10 M. As the pyrene concentration is increased above 10 M, the monomer emission is quenched and a new lower-energy emission band appears due to the formation of a [py-py] exdmer. The intensity of the excimer band increases with a concentration increase. The characteristics of the... 

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