Hidenori Shinohara

A molecular-beam apparatus with a spray-jet technique for studying neutral non-volatile molecules

A molecular-beam apparatus has been newly constructed for studying neutral non-volatile molecules, consisting of (1) a sample inlet system with a supersonic nebulizer, an inlet chamber, and a pulsed nozzle, (2) a set of skimmers, and (3) a high-vacuum chamber in which pulsed-laser photoionization and mass detection are carried out. A heavy mist of sample solution is initially prepared with the nebulizer, and then stored in the inlet chamber, from which a molecular beam is ejected into vacuum through the pulsed nozzle and skimmers. In this report we want to emphasize several advantages of this technique and its broad applicability.

Molecular-beam apparatus with a spray-jet technique and its applications

We have developed a new molecular beam apparatus that utilizes a spray-jet technique both for a spectroscopic study of neutral non-volatile molecules and a molecular deposition of these molecules. The molecular-beam apparatus consists of (1) a new inlet system with an ultrasonic nebulizer, an inlet chamber and a pulsed nozzle; (2) a set of skimmers; and (3) a high-vacuum chamber equipped with a time-of-flight mass spectrometer (TOFMS) and a substrate introduction unit. In this report, we want to emphasize several unique characteristics and the broad applicability of this molecular-beam apparatus as well as to discuss some experimental results on several typical molecules.

Spray-Jet Technique for Studying Nonvolatile Functional Molecules: Comparison of Different Spray-Jet Inlet Systems

The spray-jet technique enables us to produce a molecular beam of non-volatile molecules under high vacuum from sprayed mists of sample solutions suspended in a carrier gas. A molecular beam apparatus and the spray-jet technique have been used together in spectroscopic studies and as a means of molecular beam deposition. During the process of developing the apparatus, we developed different spray-jet inlet systems. We compared these inlet systems in terms of the efficiency of molecular beam generation, which is evaluated by measuring the signal intensity of the multiphoton ionization time-of-flight mass spectrum (MPI–TOF MS) for a sample solution and the amount of sample consumed.

Improvement of inlet system in spray-jet molecular beam apparatus

A spray-jet molecular beam apparatus, which produces a molecular beam of neutral molecules in a vacuum from the sprayed mist of a sample solution, was previously developed. The apparatus was used in spectroscopic studies or as a means of molecular deposition. The spray-jet inlet system consisted of an ultrasonic nebulizer, an inlet chamber, and a pulsed nozzle. We report herein our experiments with alternative spray-jet inlet system that replaces the previous ultrasonic nebulizer with a pneumatic nebulizer. The efficiency of molecular beam generation was evaluated on the basis of the signal intensity of the multiphoton ionization time-of-flight mass spectra (MPI–TOFMS) for sample solutions and the amount of sample consumed. Introduction of the pneumatic spray-jet inlet system increased efficiency by a factor of 20 or more.

Analysis of a Molecular Beam Produced by the Spray-Jet Technique with Femtosecond Laser Mass Spectroscopy

We previously developed a molecular beam apparatus with the spray-jet technique to produce a molecular beam of non-volatile molecules under high vacuum from sprayed mists of sample solutions. The apparatus is used in spectroscopic studies or is a means of molecular beam deposition. We analyzed the molecular beam with femtosecond laser mass spectroscopy and conventional nanosecond laser mass spectroscopy. The information obtained from both mass spectroscopy methods provided insight into non-volatile, solvent, and carrier-gas molecules in the molecular beam.