Premium
Laser ablation of organic molecules from frozen matrices
Author(s) -
Belov Mikhail E.,
Alimpiev Sergei S.,
Mlynsky Victor V.,
Nikiforov Sergei M.,
Derrick Peter J.
Publication year - 1995
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.1290091420
Subject(s) - chemistry , laser ablation , molecule , ablation , laser , organic molecules , photochemistry , analytical chemistry (journal) , chromatography , organic chemistry , optics , aerospace engineering , physics , engineering
The technique of frozen matrix‐assisted laser ablation coupled with resonance‐enhanced multiphoton ionization and reflectron time‐of‐flight mass spectrometry was used to detect intact organic molecules directly from solutions. When frozen at the temperature of liquid nitrogen, the matrices of interest were ablated by a pulsed CO 2 single‐mode laser. The analyte molecules emerging from the ablated plume were then ionized by a tunable XeCl excimer laser‐pumped dye laser and analysed with a gridless reflectron time‐of‐flight mass spectrometer. The ablation process from an ice matrix was studied with the amino acids tryptophan and tyrosine dissolved in an aqueous ethanol solution to a concentration level of 5 × 10 −4 M. It was found that fragmentation of the analyte molecules is strongly dependent on the ablating laser fluence and that there is a laser fluence range just above the ablation threshold where the decomposition is negligible. The different fragmentation mechanisms are discussed and a cavitation under the liquid surface, causing the sonoluminescence signal from an ice matrix, was shown to be responsible for the decomposition of the analyte molecules ablated by a low photon energy IR laser. Under the appropriate conditions, the analyte molecules were found to have a low rotational temperature of about 150 K resulting from the jet‐like cooling in multiple collisions with matrix molecules.