In April 2016 Manchester eScholar was replaced by the University of Manchester’s new Research Information Management System, Pure. In the autumn the University’s research outputs will be available to search and browse via a new Research Portal. Until then the University’s full publication record can be accessed via a temporary portal and the old eScholar content is available to search and browse via this archive.

Related resources

Search for item elsewhere

University researcher(s)

Academic department(s)

Development of a novel, long-lifetime supersonic jet source for laser spectroscopy of biological molecules

Taherkhani, Mehran

[Thesis]. Manchester, UK: The University of Manchester; 2010.

Access to files

FULL-TEXT.PDF (pdf)

Abstract

A novel laser desorption system, with improved signal stability and extraordinary long lifetime, is presented for the study of jet cooled biomolecules in the gas phase using vibrationally resolved photoionisation spectroscopy. Tryptophan (Trp) is used as the test substance to characterize this desorption source. Here, the surface of a moving and rotating rod (graphite/Trp, 3mm diameter and 6 mm length) is exposed to a pulsed desorption beam from a Nd:YAG (1064 nm) laser running at 20Hz (Continuum Minilite).The characteristics of the source developed here and its properties with respect to cooling and stability have been investigated. Good control over the rod movement and the delivery of the IR beam result in a highly stabilized source with no noticeable fragmentation products.The combination of premixing within the source and using a pellet has made it possible to produce a stable jet-cooled beam of Trp, which lasts for several weeks without changing the sample. Additionally, the stability and signal to noise ratio has been improved by averaging the signal over the entire sample pellet by synchronizing the data acquisition with the rotation of the sample rod. The results demonstrate how a combination of the above helps to produce stable time of flight (TOF) signal and good quality one- and two-colour resonant two-photon ionisation (R2PI), photoionisation efficiency (PIE) and mass analyzed threshold ionization (MATI) spectra of Trp. The existence of six low-lying conformers of Trp in the gas phase has been confirmed. The first MATI spectrum of an isolated biomolecule (Trp) via R2PI for the determination of IE with high accuracy as ± 3 cm-1 has been recorded.