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Title: Gas Phase Chromatography of some Group 4, 5, and 6 Halides

Gas phase chromatography using The Heavy Element Volatility Instrument (HEVI) and the On Line Gas Apparatus (OLGA III) was used to determine volatilities of ZrBr4, HfBr4, RfBr4, NbBr5, TaOBr3, HaCl5, WBr6, FrBr, and BiBr3. Short-lived isotopes of Zr, Hf, Rf, Nb, Ta, Ha, W, and Bi were produced via compound nucleus reactions at the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory and transported to the experimental apparatus using a He gas transport system. The isotopes were halogenated, separated from the other reaction products, and their volatilities determined by isothermal gas phase chromatography. Adsorption Enthalpy (ΔHa) values for these compounds were calculated using a Monte Carlo simulation program modeling the gas phase chromatography column. All bromides showed lower volatility than molecules of similar molecular structures formed as chlorides, but followed similar trends by central element. Tantalum was observed to form the oxybromide, analogous to the formation of the oxychloride under the same conditions. For the group 4 elements, the following order in volatility and ΔHa was observed: RfBr4 > ZrBr4 > HfBr4. The ΔHa values determined for the group 4, 5, and 6 halides are in general agreement with other experimental data and theoretical predictions. Preliminary experiments were performed on Me-bromides.more » A new measurement of the half-life of 261Rf was performed. 261Rf was produced via the 248Cm(18O, 5n) reaction and observed with a half-life of 74-6+7 seconds, in excellent agreement with the previous measurement of 78-6+11 seconds. We recommend a new half-life of 75±7 seconds for 261Rf based on these two measurements. Preliminary studies in transforming HEVI from an isothermal (constant temperature) gas phase chromatography instrument to a thermochromatographic (variable temperature) instrument have been completed. Thermochromatography is a technique that can be used to study the volatility and ΔHa of longer-lived isotopes off-line, Future work will include a comparison between the two techniques and the use of thermochromatography to study isotopes in a wider range of half-lives and molecular structures.« less
Authors:
 [1]
  1. Univ. of California, Berkeley, CA (United States)
Publication Date:
OSTI Identifier:
6524
Report Number(s):
LBNL--42352
TRN: US200305%%756
DOE Contract Number:
AC03-76SF00098
Resource Type:
Thesis/Dissertation
Resource Relation:
Other Information: TH: Thesis (Ph.D.); Supercedes report DE00006524; Submitted to the Univ. of California, Dept. of Chemistry, Berkeley, CA (US); PBD: 1 Oct 1998; PBD: 1 Oct 1998
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ADSORPTION; BROMIDES; CHLORIDES; CHROMATOGRAPHY; COMPOUND-NUCLEUS REACTIONS; CYCLOTRONS; ENTHALPY; HALF-LIFE; HALIDES; MOLECULAR STRUCTURE; OXYCHLORIDES; TANTALUM; THERMOCHROMATOGRAPHY; VOLATILITY