Characterization of the ground and excited states of lanthanum oxide through bimolecular oxidation of La metal with O2, NO2, N2O, and O3

Abstract

Using a beam–gas arrangement, we have studied the chemiluminescent emission which results when a thermal beam of La atoms (1750–2400 K) intersects a tenuous atmosphere (10−6 to 10−4 torr) of one of the thermal oxidants O2, NO2, N2O, or O3 (300 K). The La–O2 reaction is characterized by visible chemiluminescence from the B 2Σ+ and C 2Π states of LaO. The La–NO2, La–N2O, and La–O3 reactions are characterized by emission from the B 2Σ+, C 2Π, and D 2Σ+ states of LaO. In addition all four systems are characterized by extensive emission from the A 2Π state of LaO. From the chemiluminescent spectrum for the La–O2 system, a minimum value of 8.19±0.04 eV is deduced for the dissociation energy of lanthanum monoxide. This lower bound is in good agreement with previous mass spectrometric determinations (8.28±0.11 and 8.38±0.2 eV). We discuss the temperature dependence of the four chemiluminescent reactions deducing an upper bound for the heat of vaporization of lanthanum metal. We combine the results of our temperature dependent studies with reactant–product correlations and demonstrate the manner in which this blend can be used to elucidate the significance and dynamics of reaction of low lying atomic states in the oxidation reactions of high temperature metallic beams.

Excited Electronic State Cross Sections for Group 3 Halide and Oxide Production: Evaluating Relative Excited-State Quantum Yields

“…The applied corrections are based on the data obtained from prior kinetic analyses. 3,4 The attenuation correction does not alter the order of magnitude of the excited-state cross section which we determine. Because the distance across the zone viewed by our detector system is negligible when compared with the distance from the oven orifice to the detected volume element, further correction for attenuation across the viewing zone is not necessary.…”

Time-sliced ion-velocity imaging study of the reaction Y + O2→ YO + O

“…Because the chemiluminescence analysis of these excited states provides vibrational and rotational state distributions, there have been a significant number of experimental studies of reaction dynamics since more than 30 years ago. [1][2][3][4][5][6][7] Recently, we have studied the reaction of Y with O 2 , reaction (1), using the crossed-beam chemiluminescence and laser-induced fluorescence (LIF) techniques at several collision energies. 8 In this reaction, YO in the X 2 S + , A 0 2 D, and A 2 P states are accessible from the ground state reactants: Y(a 2 D 3/2,5/2 ) + O 2 (X 3 S À g ) -YO(X 2 S + , A 0 2 D, A 2 P) + O( 3 P J ), D r H 0 0 = À221 kJ mol À1 .…”

Reaction dynamics of V(aFJ4)+NO→VO(XΣ−4)+N studied by a crossed-beam laser-induced fluorescence technique

“…8 For the reactions of Sc, Ti, and V with a given OX, this model predicts that the rate constants should increase as k͑Sc͒ Ͻ k͑Ti͒ Ͻ k͑V͒ since the energy differences of the 3d n−2 4s 2 state and 3d n−1 4s 1 first excited state are 1.43, 0.81, and 0.26 eV, for Sc, Ti, and V, respectively. [29][30][31][32][33][34][35][36] Recently Luc and co-workers measured the laser-induced fluorescence of ScO͑X 2 ⌺ + , v =0͒ formed by the reaction, Sc+ NO → ScO + N, in the beam-gas configuration. 9 An alternative mechanism proposed is an electron transfer mechanism.…”