Isotopically selective dissociation of COCl₂molecules in the radiation field of a pulsed CO laser

Abstract

Gamma and conversion electron radiations following the decay of 1.7 s 123mC~ and 5.9 min lZsCs have been studied in singles and coincidence with mass-separated sources at the ISOLDE facility. Evidence for a 61.7 keV E3 transition, de-exciting the yisomeric state of I2ks, has been found. A scheme for the 123Cs ground-state decay including 11 new low-spin levels has been constructed. Log ff values have been calculated; limits on possible spins are deduced which invalidate in particular the previous J = { assignment for the 180.6 keV level in '"Xe. The results are discussed in the frame of odd-mass neutrondeficient Cs and Xe systematics. RADIOACTIVITY 123mC~, 123Cs (from La(p, 3p14n)), E,= 600 MeV, on-line massseparated sources; measured T1/2, E,, I,, E,, I,, yy coin, y ce coin; L23Cs, L23Xe; deduced levels, J , n, log fl. Ge(Li), Si(Li) and plastic detectors.

Isotopically Selective Infrared Multiphoton Dissociation of 2,3-Dihydropyran

“…The oxygen isotopes are widely used as a tracer such as diagnostic of cancer by positron emission tomography. Laser separation of the oxygen isotopes has been studied by UV dissociation of O 2 and D 2 CO, by IR−UV dissociation of OCS, and by isotopically selective infrared multiphoton dissociation (IRMPD) of many kinds of molecules: (CH 3 ) 2 O, – COCl 2 , CF 3 CH 2 OH, C 4 H 8 O, , (CF 3 ) 2 O, , (C 3 H 7 ) 2 O, , C 3 H 7 OCH 3 , CrO 2 F 2 , C 4 F 9 COI, (C 2 H 5 ) 2 O, C 4 H 9 OCH 3 , C 5 H 10 O and (CF 3 ) 2 CO . The enrichment factor of 18 O, which is defined as the ratio of the [ 18 O]/[ 16 O] in dissociation products after single laser pulse irradiation to that in the molecules before irradiation, is low for these molecules except (C 3 H 7 ) 2 O, the largest value for which was 350 .…”

Multiphoton Isotope-Selective Dissociation of Formic Acid Molecules under Action of a Free Electron Laser

“…A very large body of experimental and theoretical work on infrared multiphoton dissociation (MPD) has been accomplished since such reactions were first described over 20 years ago. − Of that work, a substantial proportion is concerned with isotope-specific MPD. − Isotopic enrichment in the gas phase of small molecules has been accomplished for sulfur, − oxygen, − hydrogen, − silicon 24 and multiple elements from the same compound. − The most extensive work has been done on carbon isotopes and most often with CO 2 lasers. − Carbon istotopic enrichment has been observed in single-wavelength, single-component reactants, − multiple-wavelength (usually two or more CO 2 laser lines) conditions 28-30 and in two-component, two-step processes. − …”

“…[1][2][3][4] Of that work, a substantial proportion is concerned with isotopespecific MPD. Isotopic enrichment in the gas phase of small molecules has been accomplished for sulfur, [6][7][8][9] oxygen, [10][11][12][13] hydrogen, [14][15][16][17][18] silicon 24 and multiple elements from the same compound. [19][20][21][22][23] The most extensive work has been done on carbon isotopes and most often with CO 2 lasers.…”