Optical transient absorption spectroscopy of LaO produced by pulsed laser ablation of La2O3》.pdfVIP

Spectrochimica Acta Part A 56 (1999) 171–177 www.elsevier.nllocatesaa Optical transient absorption spectroscopy of LaO produced by pulsed laser ablation of La2O3 Yongxin Tang, Xinju Yang, Xiannian Liu, Qizong Qin * Laser Chemistry Institute, Fudan Uniersity, 200433, Shanghai, People ’s Republic of China Received 8 April 1999; accepted 24 May 1999 Abstract Temporally and spatially resolved absorption spectrometry has been used to study molecular LaO absorption in laser ablated plume from an La2O3 target The absorption time-of-flight (TOF) spectra of ground-state LaO molecules were measured The TOF spectra indicate that only one component is observed in vacuum and in an Ar ambient, while there are two component, a fast and a broad slow component, observed at higher O2 pressure. The absorbance of LaO molecules decreases gradually with increasing ambient gas pressure. The dependence of the absorbance of LaO on the detection distance can be fitted by an exponential decay equation. The shock wave model is used to describe the behavior of ground state LaO molecules in high O2 pressure region. © 2000 Elsevier Science B.V. All rights reserved. Keywords: Absorption spectrometry; LaO; Laser ablation; TOF spectrum 1. Introduction raphy and ion probe method are employed to investigate the dynamic process of laser ablation As a highly versatile technique, pulsed laser [3–6]. Recentl