Optical-IR double resonance spectrum of the a(3)A(2) triplet levels coupled by intramolecular interactions to the rotational levels of the A(1)A(2) singlet state was measured for H2CS excited to a single rotational level of the vibrationless state. The spectrum was recorded for the J(1) = 4, K-a(1) = 1, K-c(1) - 3 (4(13)) level. The IR field influence on the fluorescence decay of H2CS excited to the level discussed was also investigated. Theoretical model was used to interpret the results obtained. (C) 2004 Elsevier B.V. All rights reserved.