Showing papers by "Lester Andrews published in 1994"

Reactions of laser ablated Be atoms with O2: Infrared spectra of beryllium oxides in solid argon

Abstract: Pulsed‐laser ablated beryllium atoms codeposited with O2 in excess argon at 10 K yielded new beryllium–oxygen molecules. The initial reaction to make BeO is endothermic, but activation energy is provided by hyperthermal Be atoms. A strong band at 1572.9 cm−1 and a weak band at 398.9 cm−1 gave oxygen isotopic shifts consistent with a BeO diatomic molecule and are assigned to the O2–BeO complex analogous to the Ar–BeO complex. A sharp band at 1413.2 cm−1 exhibited an oxygen isotopic triplet with 16,18O2 and shifts appropriate for linear OBeO. A nearly coincident band at 1412.4 cm−1 gave an isotopic doublet and shifted in agreement with linear BeOBe. Quantum chemical calculations at the second‐order many‐body perturbation theory [MBPT(2)] level predict 3Σ ground states and ν3 fundamentals at 1422.5 and 1418.2 cm−1 for OBeO and BeOBe, respectively, in excellent agreement with the observed values. Three bands at 1131.2, 866.3, and 522.4 cm−1 increased together on photolysis, yielded isotopic triplets, and agreed with MBPT(2) calculations for rhombic Be2O2. A sharp photosensitive band at 988.6 cm−1 gave oxygen isotopic shifts consistent with another linear OBeO species and is tentatively assigned to the molecular anion. An intense band at 1465.1 cm−1 that appeared on annealing gave oxygen isotopic shifts in agreement with calculations for linear BeOBeO. Two bands at 1288.9 and 1264.1 cm−1 appeared on photolysis and gave isotopic triplets and shifts that are in excellent agreement with calculations for branched BeBeO2. Annealing produced bands at 871.8 and 436.1 cm−1 that decreased on photolysis and are assigned to BeO3.

Pulsed laser evaporated magnesium atom reactions with hydrogen : infrared spectra of five magnesium hydride molecules

Abstract: Pulsed laser ablated magnesium atoms were reacted with molecular hydrogen to determine reaction products. The predominant ones are MgH and linear MgH{sub 2}. HMgMgH, (MgH){sub 2}, and HMg(H){sub 2}-MgH are also evident. Photoactivation of Mg{sub 2} causes an increase of HMgMgH and (MgH){sub 2} dimer formation. Annealing increased H{sub 2} complexing with MgH and MgH{sub 2}. 32 refs., 5 figs., 4 tabs.

Matrix IR spectra of the products from fluorine molecule, chlorine molecule, and chlorine fluoride (ClF) reactions with pulsed-laser evaporated uranium atoms

Abstract: Pulsed Nd:YAG laser ablated uranium atoms were codeposited with F[sub 2] and excess Ar onto a CsI window at 12 K. Infrared spectra revealed the presence of several uranium fluorides including the previously characterized UF[sub 4], UF[sub 5], and UF[sub 6]. Lower laser energy favored new absorptions at 400, 446, 496, and 561 cm[sup [minus]1]. These product absorptions increased stepwise during annealings which permitted diffusion and reaction of the fluorine. Similar studies with ClF produced the above absorptions plus a new band at 554 cm[sup [minus]1] which is tentatively assigned to ClF[sub 2][sup [minus]]. The first bands appearing at 400 and 446 cm[sup [minus]1] are assigned to UF and UF[sub 2], respectively. The 496- and 561-cm[sup [minus]1] bands are tentatively assigned to UF[sub 3] and F[sub 3][sup [minus]], respectively. Finally, uranium atoms were reacted with Cl[sub 2]. In addition to several absorptions due to UCl[sub 4], a new doublet at 312 and 308 cm[sup [minus]1] is assigned to UCl[sub 2].

Infrared spectra of binary selenium–nitrogen species formed by condensation of microwave discharge products

Abstract: Condensation of a microwave discharge excited stream of argon–nitrogen–selenium gives NSe, NSe2 and NSe2+, which are characterized by IR spectroscopy with 15N, 76Se and 80Se isotopic substitution.

Matrix infrared spectrum and ab initio calculations on the pnp radical

Abstract: SAN DIEGO SUPERCOMP CTR,SAN DIEGO,CA 92186. LIMBURGS UNIV CENTRUM,DEPT SBG,B-3590 DIEPENBEEK,BELGIUM. UNIV INSTELLING ANTWERP,DEPT CHEM,B-2610 WILRIJK,BELGIUM.ANDREWS, L, UNIV VIRGINIA,DEPT CHEM,MCCORMICK RD,CHARLOTTESVILLE,VA 22901.