Diode laser absorption spectrum of cold bands of C2HD at 6500 cm−1

The absorption spectrum of acetylene-d has been observed at high resolution between 6470 and 6630 cm−1 using an external cavity diode laser. Three cold bands have been observed: the strong 2ν1 band, the weaker ν1 + ν2 + 2ν5 band, and the (ν1 + ν3 + ν5)1 band, which gains its intensity through Coriolis resonance with 2ν1. Centers of unblended lines are determined with an accuracy of approximately 10 MHz.