Smith DJ, Ledingham KW, Singhal RP, McCanny T, Graham P, Kilic HS, Tzallas P, Kosmidis C, Langley AJ, Taday PF
Department of Physics & Astronomy, University of Glasgow, Glasgow G12 8QQ. Scotland, UK.
Rapid Commun Mass Spectrom. 1999;13(14):1366-73. doi: 10.1002/(SICI)1097-0231(19990730)13:14<1366::AID-RCM644>3.0.CO;2-3.
With the development of high intensity femtosecond lasers, the ionisation and dissociation dynamics of molecules has become an area of considerable interest. Using the technique of femtosecond laser mass spectrometry (FLMS), the molecules carbon disulphide, pyrimidine, toluene, cyclohexanone and benzaldehyde are studied with pulse widths of 50 fs in the near infrared (IR) wavelength region (790 nm). Results are presented and contrasted for laser beam intensities around 10(15) and 10(16) W cm(-2). For the lower intensities, the mass spectra yield dominant singly charged parent ions. Additionally, the appearance of doubly charged parent ions is evident for carbon disulphide, toluene and benzaldehyde with envelopes of doubly charged satellite species existing in these local regions. Carbon disulphide also reveals a small triply charged component. Such atomic-like features are thought to be a strong fingerprint of FLMS at these intensities. However, upon increasing the laser intensity to approximately 10(16) W cm(-2), parent ion dominance decreases and the appearance of multiply charged atomic species occurs, particularly carbon. This phenomenon has been attributed to Coulomb explosions in which the fast absorption of many photons may produce transient highly ionised parent species which can subsequently blow apart. Copyright 1999 John Wiley & Sons, Ltd.
随着高强度飞秒激光的发展，分子的电离和解离动力学已成为一个备受关注的领域。利用飞秒激光质谱（FLMS）技术，在近红外（IR）波长区域（790nm）以50fs的脉冲宽度对二硫化碳、嘧啶、甲苯、环己酮和苯甲醛分子进行了研究。给出了激光束强度约为10(15)和10(16)W cm(-2)时的结果并进行了对比。对于较低强度，质谱产生占主导的单电荷母离子。此外，二硫化碳、甲苯和苯甲醛中双电荷母离子的出现很明显，在这些局部区域存在双电荷卫星物种的包络。二硫化碳还显示出少量的三电荷成分。这种类原子特征被认为是这些强度下FLMS的一个强烈指纹。然而，当激光强度增加到约10(16)W cm(-2)时，母离子的主导地位下降，出现了多电荷原子物种，特别是碳。这种现象被归因于库仑爆炸，即许多光子的快速吸收可能产生瞬态高度电离的母物种，随后这些母物种可能会爆炸分开。版权所有1999约翰威立父子有限公司。
