SEDL / STP / STP1141-EB / STP23620S

The Role of Valence-Band Excitation in Laser Ablation of KCl

Haglund, RF
Vanderbilt University, Nashville, TN

Tang, K
Vanderbilt University, Nashville, TN

Bunton, PH
Austin Peay State University, Clarksville, TN

Wang, L-J
University of Tennessee, Chattanooga, TN

Pages: 12    Published: Jan 1991

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Abstract

We present recent measurements of excited-atom and ion emission from KCl surfaces illuminated by vacuum-ultraviolet synchrotron radiation (hv = 8–28 eV) and ultraviolet laser light (hv = 4 eV). At low intensities characteristic of the synchrotron experiments, excited atoms are desorbed by simple valence-band excitation process involving the metallization of the KCl surface. At the higher intensities typical of laser desorption and ablation, we observe a strong decrease in K^* emission as a function of the number of laser shots, but an essentially constant yield of Cl^*. K⁺ and Cl^- emission at high intensities show similar behavior. The energetics of these desorption phenomena can be treated in a bond-orbital model which shows that creation of a single valence hole is sufficient to excite an ion to an anti-bonding state.