Desorption Dynamics, Internal Energies and Imaging of Organic Molecules from Surfaces with Laser Desorption and Vacuum Ultraviolet (VUV) Photoionization

Journal Article · Tue Apr 05 04:00:00 EDT 2011 · Chemistry an Asian Journal

DOI:https://doi.org/10.1002/asia.201100419· OSTI ID:1023405

Kostko, Oleg; Takahashi, Lynelle K; Ahmed, Musahid

There is enormous interest in visualizing the chemical composition of organic material that comprises our world. A convenient method to obtain molecular information with high spatial resolution is imaging mass spectrometry. However, the internal energy deposited within molecules upon transfer to the gas phase from a surface can lead to increased fragmentation and to complications in analysis of mass spectra. Here it is shown that in laser desorption with postionization by tunable vacuum ultraviolet (VUV) radiation, the internal energy gained during laser desorption leads to minimal fragmentation of DNA bases. The internal temperature of laser-desorbed triacontane molecules approaches 670 K, whereas the internal temperature of thymine is 800 K. A synchrotron-based VUV postionization technique for determining translational temperatures reveals that biomolecules have translational temperatures in the range of 216-346 K. The observed low translational temperatures, as well as their decrease with increased desorption laser power is explained by collisional cooling. An example of imaging mass spectrometry on an organic polymer, using laser desorption VUV postionization shows 5 mu m feature details while using a 30 mu m laser spot size and 7 ns duration. Applications of laser desorption postionization to the analysis of cellulose, lignin and humic acids are briefly discussed.

• Research Organization: Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, CA (US)
• Sponsoring Organization: Chemical Sciences Division
• DOE Contract Number: AC02-05CH11231
• OSTI ID: 1023405
• Report Number(s): LBNL-4658E
• Journal Information: Chemistry an Asian Journal, Journal Name: Chemistry an Asian Journal Journal Issue: 11 Vol. 6; ISSN 1861-4728
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
99 GENERAL AND MISCELLANEOUS
CELLULOSE
CHEMICAL COMPOSITION
DESORPTION
DNA
FRAGMENTATION
HUMIC ACIDS
LASERS
LIGNIN
MASS SPECTRA
MASS SPECTROSCOPY
ORGANIC POLYMERS
PHOTOIONIZATION
SPATIAL RESOLUTION
THYMINE
synchrotron VUV
desorption dynamics
nucleic acids
imaging mass spectrometry
scanning probe microscopy