Hyperfine and Λ-doubling parameters for the v = 1 state of NO from infrared-radiofrequency double resonance

Hyperfine Λ-doubling transitions have been measured for a number of rotational levels with 2.5 ≤ J ≤ 20.5 in the ${}^2\text{Π}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{v = 0}\text{and}\text{1}$ states of ¹⁴N¹⁶O. The measurements were made with infrared-radiofrequency double-resonance spectroscopy, utilizing close coincidences between CO laser lines and NO 1-0 band transitions in the 5.4-μm region. A combined fit of the present and previous data gives new information for NO in the v = 1 state: greatly improved Λ-doubling parameters and the first determination of hyperfine interaction parameters.