Machine A was the first apparatus in the Continetti lab. It has been used in studies of the dissociative photodetachment of O4-, dissociation dynamics of the triplet states of ozone and in studies of organic anions and radicals. Machine A is currently being fitted with an Electrospray Ionization (ESI) source which will enable us to examine the energetics and dissociation dynamics of oxygenated radicals important in the combustion chemistry of biofuels as well as biologically relevant anions including the chromophores for the green fluorescent protein (GFP) and photoactive yellow protein (PYP).
Up until these new modifications, Machine A was capable of accelerating anions created via either electron impact on a supersonic expansion of gas or ESI to up to 10keV. With the new electrostatic LINAC, large anions can be accerlated up to 40 keV, improving the neutral detection efficiency considerably. Once the precursor anions are mass selected by time-of-flight they are irradiated by a pulse from either an Nd:YAG or Ti:Sapphire laser system. Machine A can detect one photoelectron and up to three neutral photofragments in coincidence from each laser-ion beam crossing. Both detectors record time-of-arrival and 2D position data, from which the full three-dimensional velocity distribution of the photoelectrons and the photofragments can be recreated.
If you would like to see some references for the work done on this apparatus, please go to our publications page. For a general description of the work done on this type of machine, please read Reaction Dynamics of Transient Species.
Shown above is a picture of the A machine. The sections visible are (from right to left) the source, the acceleration region, the time of flight region. The detector region is barely visible but can be better seen in the picture below.
More photos of Machine A can be found in the photo gallery.
Last Updated February 14, 2014