Abstract
A new instrument for studying the behavior of laser-desorbed bio-organic molecules is described. The instrument consists of a large diameter vacuum chamber containing a tiltable sample holder in the center, a fixed beam path for laser irradiation and two individual time-of-flight systems, one of them being rotatable around the center of the chamber. Velocity and intensity distributions of ions can be obtained as a function of the angle of incidence of the laser beam and the ion ejection angle with respect to the sample surface. Velocity and kinetic energy distributions show strong differences for different ions ejected from single crystals of 2,5-dihydroxybenzoic acid (DHB). Distributions of the dehydrated molecular ion of DHB (the most intense signal in the spectrum) are strongly peaked forward in intensity and kinetic energy. The characteristics of this hypersonic jet of ions have been investigated as a function of the laser irradiance and the focus diameter. The lowest mean velocities have been observed for large focus diameters ( d ≈ 180 μm) at threshold irradiance. Under focused conditions ( d ≈ 10 μm) mean kinetic energies of ions rose by a factor of 4 to 25 for threshold to 6 times threshold irradiance, respectively.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
