High-Pressure Tuning of One- and Two-Photon-Induced Fluorescence of an Organic Crystal NDPB

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Molecules, spectroscopy, kinetics, environment, & general theory, 1997-08, Vol.101 (32), p.5753-5757
• Main Authors: Dreger, Z. A, Yang, G, White, J. O, Drickamer, H. G
• Format: Article
• Language: English
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/jp971435k

We report strongly pressure-dependent up-conversion fluorescence from an organic crystal, 4-(p-nitrophenyl)-3,4-dihydropyrazo[c]-benzo[b]morpholine (NDPB). The fluorescence has a similar pressure dependence following both one- and two-photon excitation. In both cases, we observe a significant shift of the emission spectrum to lower energies and decrease of emission intensity in a relatively narrow pressure range (0−20 kbar). Time-resolved measurements of fluorescence decay yield two lifetimes corresponding to the local and charge-transfer state, which decrease with pressure. Similar pressure dependence of the emission energies and lifetimes in one- and two-photon-induced fluorescence indicate that in both cases the same excited states participate in the fluorescence. The same decrease of fluorescence intensity in both cases indicates that the one- and two-photon absorption spectra have similar pressure dependence.