Knowledge Bank

In an effort to extend the previous $analysis1$ of the rotation-vibration spectrum of HDO, with emphasis on the resonating vibrational states (100,020) and (110-030), we have re-examined the absorption of partially deuterated water vapor in the spectral regions 2400-3495 and $4022-4400cm-1$. With effective spectral resolution of $\sim 0.03cm-1$ and a heated long-path cell at low pressure, many new lines attributable to HDO have been observed and analyzed. With the exception of the 030 levels with $K⩾3$, the main features of the earlier work have been confirmed, but the analysis extends to much higher rotational energies and leads to improved molecular constants. All the observed bands, although predominantly Type A, show type-B components; the B/A intensity ratios depend on the effective momenta.