James L. Gole

Chemiluminescence spectra of ScO and YO: Observation and analysis of the A′ 2Δ–X 2Σ+ band system

A new band system between 6200 and 7500 A has been observed in the ’’single collision’’ beam–gas chemiluminescent spectrum resulting from the reactions of Sc and Y atoms with O2. A strong, well‐developed system is observed in the YO spectrum resulting from the Y–O2 reaction. A vibrational analysis of two distinct subsystems, each consisting of double‐headed bands (ΔΛ?1), yields Te=14 531.2 cm −1, ωe′=794.0 cm−1, ωexe′=3.23 cm−1, ωe″=861.9 cm−1, ωexe″=2.95 cm−1 for the lower component, and Te=14 870.4 cm−1, ωe′=794.9 cm−1, ωe′=3.3 cm−1, ωe″=862.1 cm−1, ωexe″=3.025 cm−1 for the upper component. Semiempirical calculations predict Te=15 330.4 cm−1 for the A′ 2Δr state of YO. Perturbation calculations predict that mixing of the A 2Π state with the A′ 2Δ state of YO may be as large as 3.5%. On the basis of these calculations, the new band system is attributed to the A′ 2Δ–X 2Σ+ transition of YO. The new band system in the Sc+O2 spectrum is weaker and not as well resolved as the YO system. However, analysis of t...

Bimolecular, single collision reaction of ground and metastable excited states of titanium with O2, NO2, and N2O: Confirmation of D00(TiO)

A beam‐gas arrangement has been used to study the chemiluminescent emission which results when a thermal beam of titanium atoms (2200–2650 K) intersects a tenuous atmosphere (10−4 to 10−5 torr) of thermal O2, NO2, and N2O molecules (300  K). The visible chemiluminescence extends from 7000 to ∼4000 A for the titanium–O2 reaction and 7000 to ∼3000 A for the titanium–NO2 and titanium–N2O reactions. The emission which characterizes the Ti–O2 reaction corresponds predominantly to the B 3Π–X 3Δ and C 3Δ–X 3Δ band systems of titanium monoxide. Some weak emission corresponding to the c 1φ–a 1Δ band system is also observed. The emission from the Ti–NO2 and Ti–N2O reactions is considerably more complicated; however, both reactions are characterized by strong B 3Π–X 3Δ and C 3Δ–X 3Δ emission features. The Ti–N2O reaction also displays strong emission from the D–X 3Δ TiO band system. A detailed analysis of the emission spectrum resulting from the Ti–O2 reaction is presented. Although emission is observed from the sev...

Al+O3 chemiluminescence: Perturbations and vibrational population anomalies in the B 2Σ+ state of AlO

Ozone reacts with aluminum entrained in an argon buffer gas to yield the B 2Σ+–X 2Σ+ spectrum of AlO. The measured B 2Σ+ vibrational populations for this reaction follow a markedly non‐Boltzmann distribution, exhibiting local maxima at vibrational levels v′=6, 8, 12, and 14. This behavior is attributed to an initial chemical reaction Al+O3→AlO(A 2Π) +O2 followed by the collision induced rearrangement AlO(A 2Π) +Ar→AlO(B 2Σ+)+Ar. The spin–orbit interaction in AlO connects ro‐vibronic levels of the A 2Π and B 2Σ+ states. Consequently, collisional energy transfer is particularly efficient for the most strongly perturbed levels of the B 2Σ+ state. For Al+N2O, an approximate Boltzmann distribution in the AlO B 2Σ+ state population indicates that this reaction proceeds by a differing mechanism. Consistent with the proposed mechanism for Al+O3 is the appearance of ’’extra’’ band heads representing normally Franck–Condon forbidden A–X transitions which become allowed because of a small admixture of B 2Σ+ characte...

Single collision chemiluminescence studies of scandium and yttrium oxidation with O2, NO2, N2O and O3

Abstract The chemiluminescent reactions of Sc and Y atoms with O 2 , NO 2 , N 2 O, and O 3 have been studied under single-collision conditions, using a beam-gas arrangement. The reactions of Sc and Y with O 2 are characterized by emission from the A 2 Π and the previously unobserved A ·2 Δ states of ScO and YO. The reactions of Sc and Y with NO 2 , N 2 O and O 3 result in emission from the A 2 ‖ and B 2 Σ + states of ScO and YO. In addition, emission from at least one previously unobserved electronic state, lying higher in energy than the B 2 Σ + state, is observed in the emission resulting from the Sc-O 3 , Sc-N 2 O, Y-O 3 and Y-N 2 O reactions. From the A 2 Π-X 2 Σ + chemiluminescent spectra for the SC-O 2 and Y-O 2 systems, minimum values of 7:13 ± 0.1 eV for the dissociation energy of ScO, and 7.50 ± 0.1 eV for the dissociation energy of YO are deduced. These lower bounds are in good agreement with previous mass spectrometric determinations of these quantities. Upper and lower bounds to the effective rotational temperature of ScO (B 2 Σ + , ν′ = 0) formed in the Sc-NO 2 reaction are determined from rotational structure observed in the B-X chemiluminescent spectrum. Measurements of the dependence of the chemiluminescent intensity on oxidant pressure and metal temperature indicate that all of the reactions studied are first order with respect to both ground state metal atom and oxidant molecule number densities. Relative rate constants for formation of product vibrational and electronic states are determined from the chemiluminescent spectra. In several instances, these rates are found to deviate quite substantially from those predicted on the basis of prior statistical distributions obtained with no dynamical constraints

Ab initio study of the electronic structure of Li2

We have performed SCF–CI calculations on the ground states of Li2 and its anion. We predict a value aof 0.45 eV for the adiabatic electron affinity of Li2 and a value of 0.86 eV for the dissociation energy of Li2 −. Thus, the bond strength of the anion is nearly the same as that of the neutral parent. This indicates that the simple MO picture, describing the anion as being formed by the addition of an electron to the antibonding 2σu orbital, is not adequate. The present results are compared to the recent equation‐of‐motion calculation of the Li2 electron affinity by Andersen and Simons.

The temperature dependence of ''single collision'' bimolecular beam--gas chemiluminescent reactions. I. Theory

We consider a ’’single collision’’ bimolecular beam–gas chemiluminescent reaction in which a metal beam formed effusively intersects a tenuous atmosphere of oxidant gas (10−4 to 10−6 torr) resulting in the emission of visible radiation from excited electronic states of the reaction products. The kinetics of this beam–gas chemiluminescent reaction are studied in order to derive the relationship between the chemiluminescent intensity and the parameters of the beam–gas reaction. A formula is derived which relates the relative single collision chemiluminescent intensity to reactant mass and temperature, the enthalpy of vaporization or sublimation of the (metal) beam source material (ΔHsub, ΔHvap), and the Arrhenius activation energy (Eexp) for formation of products in particular, chemiluminescing, excited electronic states. The determination of the temperature dependence of the observed chemiluminescence provides an upper bound to ΔH vaporization (ΔHsub). If ΔH is accurately known through independent studies,...

The temperature dependence of ’’single collision’’ bimolecular beam–gas chemiluminescent reactions. II. Experimental studies

We consider ’’single collision’’ bimolecular beam–gas chemiluminescent reactions in which a metal beam formed effusively intersects a tenuous atmosphere of oxidant gas (10−4–10−6 torr) resulting in the emission of visible radiation from excited electronic states of the reaction products. From recently derived relationships which allow the determination of the temperature dependence for the observed chemiluminescence we deduce upper bounds for ΔH vaporization (ΔHsub). In addition, for systems in which ΔH is accurately known through independent studies Eexp may be evaluated. Derived relationships are demonstrated experimentally through studies of ten bimolecular reactions. We consider the reaction of strontium atoms and fluorine molecules. Here, reaction occurs with one internal state of the metal atom (ground 1S0 states). ΔHsub(Sr), Eexp(SrF, C2Π), and Eexp(SrF, D2Σ+) are determined by monitoring the chemiluminescence from the SrF C2Π and D2Σ+ excited electronic product states. By combining the determined ...

“Single collision” chemiluminescent studies of the LaOCS reaction—vibrational analysis of the LaS C2Π-X2Σ+ system and determination of D00(LaS)

Abstract The chemiluminescent emission of lanthanum monosulfide resulting from the reaction of lanthanum with carbonyl sulfide was studied. A band system extending from 4300 to 4800 A was observed. It was already analyzed and identified as the C 2 Π-X 2 Σ + transition. A lower bound of 136.15 ± 0.42 kcal/mole was calculated for D 0 0 (LaS). The spectra and structure of LaS are compared to LaO.