High-resolution laser spectroscopy on the A3Π ← X3Σ− transition of NH

Abstract

In a molecular beam, laser-induced fluorescence experiment, rotational spectra of the A3Π, ν = 0 ← X3Σ−, ν = 0 transition of the NH free radical were measured at 336 nm with high resolution. From more than 300 completely resolved hyperfine lines, the hyperfine structure of the A3Π excited state and the X3Σ− ground state could be analyzed. For the first time, the hyperfine coupling constants aN.H, bN.H, cN.H, dN.H, eQq1, and eQq2 in the A3Π state were determined. Also, the nuclear quadrupole coupling constant eQq1 in the X3Σ− ground state was obtained.