High Resolution Photoionization Spectrum of HBr Measured With Frequency Tripled Laser Radiation

The photoionization spectrum of HBr around the first ionization limit was measured at resolution of up to 5 x 10−4 nm. The ionizing vacuum ultraviolet radiation was generated by frequency tripling of the second harmonic output of a dye laser. Three sets of Rydberg series, each converging to the ground state (2Π3/2) of HBr+, were observed on the longer wavelength side of the ionization limit. By extrapolation of the Rydberg series, the ionization potential of HBr was determined to be 11.666 ± 0.001 eV.