Sm. Belotserkovets et al., INSTALLATION FOR GENERATING MOLECULAR CLUSTERS IN A PULSED SUPERSONICBEAM, Instruments and experimental techniques, 35(5), 1992, pp. 932-936
An installation for generating and recording pulsed beams of molecular
clusters is described. The installation contains a pulsed supersonic
nozzle, a molecular-beam generation system, and a pulsed-beam detector
. The detector is an MS 7303 quadrupole mass-spectrometer and a vacuum
system. The measurement hardware contains an IBM PC/AT 286 and CAMAC
crate and is used to record and to control the experiment. The range o
f operating pressures in the beam source chamber is 10(-5) torr-5 atm;
the duration of the nozzle's open state ranges from 300 musec to 1 ms
ec; and the pulse frequency is 1-20 Hz. The beam parameters were evalu
ated by a numerical simulation of the gas-carrier's beam shape which g
ives a Mach number of M congruent-to 3, a beam temperature of congruen
t-to 65-degrees-K, and a beam source pressure of 500 torr. The lines o
btained from the mass spectrum of the beams showed a mixture of size c
lusters. The line identification procedure is based on a profile analy
sis of the gas pulse. Clusters of formic acid, alcohol, methyl iodide,
sulphur dioxide, benzene, etc. and containing up to twelve molecules
were obtained and identified on the installation.