Spectroscopy of the acetylenic C-H stretch of propyne-d(3) in the region of the second overtone

The rovibrational overtone spectrum of propyne-d(3) (CD3-C dropC-H) in the region of the second overtone of the acetylenic C-H stretch (3v(1)) was mon itored employing photoacoustic laser absorption spectroscopy. Comparison of the observed spectrum with that simulated for a symmetric-top molecule rev ealed the assignment. The observed spectrum comprises the main parallel ban d, 3v(1), overlapped by two hot bands identified as 3v(1) + v(10) - v(10) a nd 3v(1) + 2v(10) - 2v(10), where v(10) is the degenerate C-C dropC bend. T he bands are resolved for the total angular momentum, allowing derivation o f the parameters of the 3v(1) state and of some of those of the hot bands. (C) 2001 Academic Press.