Selective laser-induced breakdown of xenon

Selective excitation of laser-induced breakdown of xenon by nanosecond laser pulses in the spectral range of 420--600 nm and light intensity of 10¹¹ W/cm² has been studied. A number of multiphoton resonances have been identified in the breakdown excitation spectra and the excitation conditions within the focal volume have been determined from the ac Stark shift of the resonances. It has been shown that the breakdown initiation is influenced by odd harmonics of the laser light, which are generated in the focal volume. The phase-matched harmonic field induces the breakdown near some of the multiphoton resonances, while this field is able to suppress the breakdown under on-resonance excitation due to destructive interference between optical transitions. Taking into account the internally generated harmonics of the laser field, the interpretation of some of the previous experimental results is reconsidered.