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Efficient coupling of nanosecond laser pulses with the cluster medium: Generation of hydrogen‐like [C] 5+ atomic ions
Author(s) -
Sharma Pramod,
Das Soumitra,
Vatsa Rajesh K.
Publication year - 2014
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.7085
Subject(s) - chemistry , coulomb explosion , ion , atomic physics , ionization , laser , mass spectrometry , reflectron , nanosecond , analytical chemistry (journal) , time of flight mass spectrometry , optics , physics , organic chemistry , chromatography
RATIONALE Clusters exhibit diverse photochemical behavior as a function of laser parameters, i.e. wavelength, pulse duration and intensity. One such aspect of cluster photochemistry is the generation of energetic multiply charged atomic ions, upon efficient interaction of clusters with intense laser pulses. In the present work, mass spectrometric investigations have been carried out on clusters of tetrahydrofuran (THF, C 4 H 8 O) – a saturated cyclic ether – subjected to nanosecond laser pulse (spanning from UV to IR wavelength range) with the aim of shedding light on the complex mechanism of laser‐cluster interactions, which is still ambiguous. METHODS THF clusters, generated via supersonic expansion of room‐temperature THF vapours seeded in argon, were subjected to gigawatt intensity laser pulses (355, 532 and 1064 nm) obtained from a nanosecond Nd:YAG laser. The ions generated upon laser‐cluster interaction were characterized using a time‐of‐flight mass spectrometer. RESULTS At 355 nm, THF clusters exhibit the usual multiphoton dissociation/ionization behavior while, at 532 nm, observation of multiply charged atomic ions of carbon (up to [C] 4+ ) and oxygen (up to [O] 3+ ) was ascribed to Coulomb explosion of THF clusters. For studies carried out at 1064 nm, multiply charged atomic ions of carbon up to [C] 5+ having an ionization energy of ~392 eV were observed, at a laser intensity of 10 10 W/cm 2 . CONCLUSIONS The observation of [C] 5+ atomic ions signifies efficient coupling of the laser energy with the cluster medium, using a nanosecond laser pulse. The results have been rationalized on the basis of a three‐stage cluster ionization mechanism, suggesting the crucial role of the threshold laser intensity for initiating ionization within the cluster and generation of optimum charge centers for efficient extraction of energy from the laser pulse. Copyright © 2014 John Wiley & Sons, Ltd.