AΠ1→Δ1Band of NH and the Corresponding ND Band

Abstract

A ${}_{}{}^1{}_{}{}^{}\Pi \to {}_{}{}^1{}_{}{}^{}\Delta$ band of NH at 3240A is compared with the corresponding ND band at 3235A. The rotational constants of the two bands are related within the limits of experimental errors in the way expected theoretically. It is necessary to take into account that the lowest vibrational state has half a quantum of vibrational energy. The existence of zero point vibrational energy appears also in the fact that the zero lines of the two bands are separated by 93.39 wave numbers. In agreement with the theoretical expectations the $\Lambda$-doubling in the ND band is smaller than in the NH band by a factor 3.511.