Supersonic molecular beam electric resonance spectroscopy and van der Waals molecules

Technical Report · Wed Sep 01 04:00:00 EDT 1982

OSTI ID:6635323

Luftman, H S

A supersonic molecular beam electric resonance (MBER) spectrometer was built to study the radiofrequency spectra of weakly bound gas phase van der Waals molecules. The instrument and its operating characteristics are described in detail. Sample mass spectra of Ar-ClF gas mixtures are also presented as an illustration of the synthesis of van der Waals molecules. The Stark focusing process for linear polar molecules is discussed and computer-simulated using both second order perturbation and variational methods. Experimental refocusing spectra of OCS and ClF are studied and compared with these trajectory calculations. Though quantitative fitting is poor, there are strong qualitative indicators that the central part of a supersonic beam consists of molecules with a significantly greater population in the lowest energy rotational states than generally assumed. Flop in as opposed to flop out resonance signals for OCS are also numerically predicted and observed. The theoretical properties of the MBER spectrum for linear molecules are elaborated upon with special emphasis on line shape considerations. MBER spectra of OCS and ClF under a variety of conditions are presented and discussed in context to these predictions. There is some uncertainty expressed both in our own modeling and in the manner complex MBER spectra have been analyzed in the past. Finally, an electrostatic potential model is used to quantitatively describe the class of van der Waals molecules Ar-MX, where MX is an alkali halide. Energetics and equilibrium geometries are calculated. The validity of using an electrostatic model to predict van der Waals bond properties is critically discussed. (DSW)

• Research Organization: Lawrence Berkeley Lab., CA (USA)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 6635323
• Report Number(s): LBL-15091; ON: DE83003303
• Country of Publication: United States
• Language: English

Related Subjects

640302* -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
74 ATOMIC AND MOLECULAR PHYSICS
ALKALI METAL COMPOUNDS
ARGON
BEAMS
CHEMICAL BONDS
CHLORINE COMPOUNDS
CHLORINE FLUORIDES
COMPUTER CALCULATIONS
COULOMB FIELD
DATA
ELECTRIC FIELDS
ELECTRIC RESONANCE
ELECTROSTATICS
ELEMENTS
EXPERIMENTAL DATA
FLUIDS
FLUORIDES
FLUORINE COMPOUNDS
FOCUSING
GASES
HALIDES
HALOGEN COMPOUNDS
INFORMATION
MASS SPECTRA
MEASURING INSTRUMENTS
MOLECULAR BEAMS
MOLECULES
NONMETALS
NUMERICAL DATA
POLYATOMIC MOLECULES
RARE GASES
RESONANCE
RF SYSTEMS
SPECTRA
SPECTROMETERS
STARK EFFECT
VAN DER WAALS FORCES