Optimum molecular constants and term values for the <i>X</i>²Π(ν ≤ 5) and <i>A</i>²Σ⁺(ν ≤ 3) states of OH

Abstract

Least-squares fits of 1618 A 2 Σ + –X 2 Π frequencies, 774 X 2 Π vibration–rotation frequencies, and 125 microwave frequencies have been made to effective 2 Σ + and 2 Π Hamiltonians containing adjustable parameters for each vibrational level. The fitted parameters from each band, some of which included the microwave frequencies simultaneously, have been merged to obtain a set of 13 A ↔ X band origins and 91 single-valued parameters for A 2 Σ + , ν ≤ 3 and X 2 Π, ν ≤ 5. The set of parameters reproduces the experimental frequencies with residuals which on the average are only about 1.12 times larger than the estimated precisions of the data. Tables of term values calculated from the merged constants are reported for the two states.