Luo Guanghong, Chen Yong, Daniels Hugh, Dubrow Robert, Vertes Akos
Department of Chemistry, Institute for Proteomics Technology and Applications, The George Washington University, Washington, DC 20052, USA.
J Phys Chem B. 2006 Jul 13;110(27):13381-6. doi: 10.1021/jp0609582.
Laser-induced desorption/ionization from silicon nanowires (SiNW) is an emerging method for mass spectrometry of small to medium-size molecules. In this new technique, we examined the internal energy transfer to seven benzylpyridinium thermometer ions and extracted the corresponding internal energy distributions. To explore the effect of the energy-deposition rate on the internal energy transfer, two lasers with significantly different pulse lengths (4 ns vs 22 ps) were utilized as excitation sources. A comparison of ion yields indicated that the SiNW substrates required 5-8 times less laser fluence for ion production than either matrix-assisted laser desorption/ionization (MALDI) or desorption/ionization on silicon (DIOS). In contrast however, the survival yield (SY) values showed that the internal energy transferred to the thermometer ions was more than (ps laser) or comparable to (ns laser) MALDI but it was significantly less than in DIOS. The internal energy transfer was only slightly dependent on laser fluence and on wire density. These effects were rationalized in terms of the confinement of thermal energy in the nanowires and of unimpeded three-dimensional plume expansion. Unlike in MALDI from CHCA and in perfluorophenyl-derivatized DIOS, for desorption from SiNWs the effect of laser pulse length on the internal energy transfer was found to be negligible.
激光诱导从硅纳米线（SiNW）解吸/电离是一种用于中小分子质谱分析的新兴方法。在这项新技术中，我们研究了七种苄基吡啶温度计离子的内能转移，并提取了相应的内能分布。为了探究能量沉积速率对内能转移的影响，使用了两种脉冲长度差异显著的激光（4纳秒对22皮秒）作为激发源。离子产率的比较表明，与基质辅助激光解吸/电离（MALDI）或硅上解吸/电离（DIOS）相比，SiNW衬底产生离子所需的激光通量要少5至8倍。然而，相比之下，存活产率（SY）值表明，转移到温度计离子的内能比MALDI多（皮秒激光情况）或与之相当（纳秒激光情况），但明显低于DIOS中的情况。内能转移仅略微依赖于激光通量和线密度。这些效应可以通过纳米线中热能的限制以及不受阻碍的三维羽流膨胀来解释。与来自CHCA的MALDI和全氟苯基衍生化的DIOS不同，对于从SiNW解吸的情况，发现激光脉冲长度对内能转移的影响可以忽略不计。
