Coulomb-explosion technique for determining geometrical structures of molecular ions
Traditional experimental techniques (e.g. studies on photon absorption or emission) for determining the sterochemical structures of neutral molecules are extremeley difficult to apply to molecular ions because of problems in obtaining a sufficient spatial density of the ions to be studied. Recent high-resolution measurements on the energy and angle distributions of the fragments produced when fast (MeV) molecular-ion beams from an electrostatic accelerator dissociate (Coulomb explode) in thin foils and in gases, offer promising possibilities for deducing the sterochemical structures of the molecular ions constituting the incident beams. Bond lengths have been determined in this way for several diatomic projectiles (H/sub 2//sup +/, HeH/sup +/, CH/sup +/, NH/sup +/, OH/sup +/, N/sub 2//sup +/, O/sub 2//sup +/, etc.) with an accuracy of approx. 0.01 A. H/sub 3//sup +/ has been demonstrated (for the first time) to be equilateral triangular and the interproton distance measured. Measurements on single fragments from CO/sub 2//sup +/, N/sub 2/O/sup +/, C/sub 3/H/sub 3//sup +/, and CH/sub n//sup +/ have revealed the gross structures of the projectiles. An apparatus has recently been constructed at Argonne to permit precise measurements on fragments in coincidence. The apparatus has been tested on a known structure (OH/sub 2//sup +/). The O-H bond length was found to be 1.0 +- 0.04 A and the H-O-H bond angle was measured as 110 --- 2/sup 0/. These values are in excellent agreement with those found in optical experiments (0.999 A and 110.5/sup 0/). This Coulomb explosion technique can be expected to be refined in accuracy and to be extended to a wide range of molecular ions whose structures are inaccessible by other means.
- Research Organization:
- Argonne National Lab., IL (USA)
- DOE Contract Number:
- W-31-109-ENG-38
- OSTI ID:
- 6427514
- Report Number(s):
- CONF-810231-5; ON: DE83010587
- Resource Relation:
- Conference: 5. international conference on ion beam analysis, Sydney, Australia, 16 Feb 1981; Other Information: Portions are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
MOLECULAR IONS
COLLISIONS
DISSOCIATION
AMMONIA
BOND LENGTHS
CARBON DIOXIDE
CHEMICAL BONDS
HELIUM HYDRIDES
HYDROGEN IONS 2 PLUS
HYDROXYL RADICALS
MEV RANGE
MOLECULAR STRUCTURE
NITROGEN
NITROGEN OXIDES
OXYGEN
CARBON COMPOUNDS
CARBON OXIDES
CATIONS
CHALCOGENIDES
CHARGED PARTICLES
DIMENSIONS
ELEMENTS
ENERGY RANGE
HELIUM COMPOUNDS
HYDRIDES
HYDROGEN COMPOUNDS
HYDROGEN IONS
IONS
LENGTH
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NONMETALS
OXIDES
OXYGEN COMPOUNDS
RADICALS
RARE GAS COMPOUNDS
640304* - Atomic
Molecular & Chemical Physics- Collision Phenomena