SEDL / STP / STP1028-EB / STP18534S

Mass Spectrometric Studies of Laser Damage in Calcium Fluoride

Nogar, NS
Los Alamos National Laboratory, Los Alamos, New Mexico

Apel, EC
Los Alamos National Laboratory, Los Alamos, New Mexico

Estler, RC
Fort Lewis College, Durango, Colorado

Pages: 8    Published: Jan 1988

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Abstract

Both electron impact- and laser ionization-mass spectrometry have been used to probe the material spalled from CaF² surfaces by the fundamental(1.06μ) and harmonic (355 nm and 266 nm) outputs from a Q-switched Nd:YAG laser. We have identified a number of gas phase products, including Ca, CaF and tentatively, CaF², and have measured their translational and internal energy distributions.

Our results suggest that while the 1.06μ experiments can be adequately modeled in terms of a single damage mechanism (likely avalanche breakdown), the short-wavelength results suggest the onset of second mechanism, perhaps multiphoton absorption. This is consistent with both the observed bimodal velocity distribution following short-wavelength damage, and with the decrease in CaF vibrational and rotational excitation.