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Proceedings of the 2021 International Symposium on Molecular Spectroscopy, 2021

Journal of Physical Chemistry A, Mar 12, 2013

The optical spectrum of the linear CuCCH molecule has been investigated for the first time, using... more The optical spectrum of the linear CuCCH molecule has been investigated for the first time, using resonant two-photon ionization spectroscopy employing ArF (193 nm) or F2 (157 nm) excimer radiation for photoionization. Scans over the range 19 400-25 200 cm(-1) were conducted, leading to the observation of three electronic band systems. These are identified as the [20.2] ã1 ← X̃ (1)Σ(+), the [23.1] Ã (1)Σ(+) ← X̃ (1)Σ(+), and the [24.7] B̃ (1)Π ← X̃ (1)Σ(+) systems, although only the first two have been rotationally resolved. The ã1 state is tentatively assigned as having (3)Π1 symmetry, becoming optically accessible through spin-orbit interaction with the B̃ (1)Π state. Vibrational assignments have provided the frequency of the Cu-C stretching mode, ν3, in the ground and all three excited states, along with both bending modes, ν4 and ν5, in the Ã (1)Σ(+) and B̃ (1)Π states, and the Cu-C≡C bending mode, ν5, in the ground state. Comparisons are made to the known electronic states of CuF, CuCl, CuBr, and CuI, and it is argued that like these molecules, the CuCCH molecule is essentially ionic in both the ground and excited states, with the ground state correlating diabatically to Cu(+) (3d(10), (1)S) + CCH(-) (X̃ (1)Σ(+)) and the excited states correlating diabatically to Cu(+) (3d(9)4s(1), (1,3)D) + CCH(-) (X̃ (1)Σ(+)).

The Journal of Chemical Physics, 1998

The first optical spectroscopic investigation of MoC has revealed a complicated vibronic spectrum... more The first optical spectroscopic investigation of MoC has revealed a complicated vibronic spectrum consisting of about 35 bands between 17 700 and 24 000 cm Ϫ1. Analysis has shown the ground state to be the ⍀ϭ0 ϩ spin-orbit component of a 3 ⌺ Ϫ state that derives from a 10 2 11 2 5 4 2␦ 2 configuration. The X 3 ⌺ 0 ϩ Ϫ rotational constant for 98 Mo 12 C was determined to be B 0 ϭ0.553 640 Ϯ0.000 055 cm Ϫ1 , giving r 0 ϭ1.687 719Ϯ0.000 084 Å. Consideration of spin-uncoupling effects in the X 3 ⌺ Ϫ state requires that this value be revised to r 0 ϭ1.6760 Å, which represents our best estimate of the true Mo-C bond length. Spectroscopic constants were also extracted for six other major isotopic modifications of MoC in this mass resolved experiment. All rotationally resolved transitions were found to originate from the ground state and terminate in electronic states with ⍀ϭ1. An attempt is made to classify the observed transitions into band systems, to rationalize the complexity of the spectrum, and to understand the bonding from a molecular orbital point of view.

The Journal of Chemical Physics, 1993

The experimental rates of predissociation of vibrational levels of the 'B1 (KL=O) excited states ... more The experimental rates of predissociation of vibrational levels of the 'B1 (KL=O) excited states of the Cd * HZ and Cd * D2 complexes are shown to be consistent with both semiclassical and quantum-mechanical pseudodiatomic theoretical treatments of the process. The 'B, pseudodiatomic potential was constructed by fitting an analytical function to the experimentally estimated Rydberg-Klein-Rees (RKR) inner and outer turning points. The potential of the repulsive 3A1 state was estimated by fitting an exponential function to the ab initio points of Boatz, Gutowski, and Simons, then adjusting the exponential parameter slightly to maximize overall agreement with the observed Cd * H2 and Cd * D, predissociation lifetimes. The best-fit repulsive curves for both the semiclassical and quantum-mechanism calculations result in slightly "outer-wall" 1B1/3A1 crossings at only 84 and 76 cm-', respectively, above the 'B, potential minimum. The 'BJ3A1 coupling matrix elements derived from both treatments were-150-160 cm-', much smaller than the 404 cm-' expected if the spin-orbit interaction were unchanged from that of the asymptotic Cd(5s5p) states. It is suggested that the apparent reduction in the coupling strength could be due to the marked change in the nature of the Cd 5pa orbital due to the strong repulsive interaction with H, in the 3A1 state and to the neglect of the anisotropy of the 'BJ3A, triatomic potential surface crossing.

The Journal of Chemical Physics, 1998

The mechanism of 4p 1 P 1 →4p 3 P J intersystem crossing ͑ISC͒ following excitation of the 4p 1 P... more The mechanism of 4p 1 P 1 →4p 3 P J intersystem crossing ͑ISC͒ following excitation of the 4p 1 P 1 level of matrix-isolated atomic zinc is investigated using a pair potentials approach. This is achieved by extending earlier ISC calculations on the Zn•RG 2 and Zn•RG 3 complexes to the square planar Zn•RG 4 and square pyramidal Zn•RG 5 species which are the building blocks of the Zn•RG 18 cluster used to represent the isolation of atomic zinc in the substitutional site of a solid rare-gas host. ISC predictions in these clusters are based on whether crossing of the strongly bound 1 A 1 states, having a 4p 1 P 1 atomic asymptote, occurs with the repulsive 3 E states correlating with the 4p 3 P J atomic level of atomic zinc. Predictions based on 1 A 1 / 3 E curve crossings for 3 E states generated with the calculated ab initio points for the Zn•RG 3 ⌺(p z) states do not agree with matrix observations. Based on similar overestimation of ISC in the Zn•RG diatomics, less repulsive Zn•RG 3 ⌺(p z) potential curves are used resulting in excellent agreement between theory and observations in the Zn-RG matrix systems. 1 A 1 / 3 E curve crossings do not occur in the Zn-Ar system which shows only singlet emission. Curve crossings are found for the Zn-Xe system which exhibits only triplet emission. The Zn-Kr system does not show a crossing of the body mode Q 2 , which exhibits a strong singlet emission at 258 nm while the waist mode Q 3 , does have a crossing, resulting in a weak singlet emission at 239 nm and a stronger triplet emission at 312 nm. The efficiency of ISC is determined from Landau-Zener estimates of the surface hopping probabilities between the 1 A 1 and the 3 E states. Differences in the application of this theory in the gas and solid phase are highlighted, indicating that the rapid dissipation of the excited-state energy which occurs in the solid must be included to obtain agreement with observations.

ManuscriptThe possibility of magnetic dipole-induced pure rotational transitions in the interstel... more ManuscriptThe possibility of magnetic dipole-induced pure rotational transitions in the interstellar medium is investigated for symmetric Hund?s case (a) linear molecules, such as H-C?C-H+(X~2?3/2u), CO2+ (X~2?3/2g), H-C?C-?C-H+ (X~2?3/2g), and N3 (X~2?3/2g). These species lackan electric dipole moment and therefore cannot undergo pure rotational electric dipole transitions. These species can undergo pure rotational transitions via the parallel component of the magnetic dipole operator, however. The transition moments and Einstein A coefficients for the allowed pure rotational transitions are derived for a general Hund?s case (a) linear molecule, and tabulated for the examples of H-C?C-H+ (2?3/2u) and H-C?C-C?C-H+ (2?3/2g). It is found that the rates of emission are comparable to collision rates in interstellar clouds, suggesting that this decay mechanism may be important in simulating rotational population distributions in diffuse clouds and for detecting these molecules by radioas...

The Journal of Chemical Physics

Two-photon ionization thresholds of RuB, RhB, OsB, IrB, and PtB have been measured using resonant... more Two-photon ionization thresholds of RuB, RhB, OsB, IrB, and PtB have been measured using resonant two-photon ionization spectroscopy in a jet-cooled molecular beam and have been used to derive the adiabatic ionization energies of these molecules. From the measured two-photon ionization thresholds, IE(RuB) = 7.879(9) eV, IE(RhB) = 8.234(10) eV, IE(OsB) = 7.955(9) eV, IE(IrB) = 8.301(15) eV, and IE(PtB) = 8.524(10) eV have been assigned. By employing a thermochemical cycle, cationic bond dissociation energies of these molecules have also been derived, giving D0(Ru+–B) = 4.297(9) eV, D0(Rh+–B) = 4.477(10) eV, D0(Os–B+) = 4.721(9) eV, D0(Ir–B+) = 4.925(18) eV, and D0(Pt–B+) = 5.009(10) eV. The electronic structures of the resulting cationic transition metal monoborides (MB+) have been elucidated using quantum chemical calculations. Periodic trends of the MB+ molecules and comparisons to their neutral counterparts are discussed. The possibility of quadruple chemical bonds in all of these...

Journal ArticleDispersed fluorescence spectroscopy has been used to study jet-cooled AgAu and Pt2... more Journal ArticleDispersed fluorescence spectroscopy has been used to study jet-cooled AgAu and Pt2 . Fluorescence resulting from the excitation of five bands of the A?X 1?+ system of AgAu was dispersed, and 51 measured ground state vibrational levels were fit to provide ground state vibrational constants of ?"e=198.2260.11 cm21 and ?"exe"=0.512?0.002 cm-1. A Franck?Condon calculation was performed using the experimental values of the ground and excited state vibrational frequencies and anharmonicities, providing an estimate of the change in bond length upon excitation of the A?X system of ?re=0.214?0.005 ?. Fluorescence resulting from four different excitations of Pt2 was dispersed, providing vibrational constants for the ground and two low-lying excited states. Ground state vibrational constants of ?e=222.3 cm-1 and ?exe=0.62 cm21 were obtained, based on the analysis of 16 measured ground state vibrational levels. In addition, a low-lying excited state was located at ...

The Journal of Chemical Physics, 2001

Dispersed fluorescence studies of the diatomic molecules MoC, RuC, and PdC are reported. New stat... more Dispersed fluorescence studies of the diatomic molecules MoC, RuC, and PdC are reported. New states identified in MoC and RuC are the ͓...͔2␦ 1 12 1 , 3,1 ⌬ 2 states and the ͓...͔2␦ 3 12 1 , 1 ⌬ 2 state, respectively. Five states are observed by dispersed fluorescence in PdC. The ground state is found to be ͓...͔2␦ 4 12 2 , 1 ⌺ ϩ , with the ͓...͔2␦ 4 12 1 6 1 , 3 ⌸ ⍀ manifold of states lying about 2500 cm Ϫ1 above the ground state. The ͓17.9͔⍀ϭ1 state of PdC is also identified as ͓...͔2␦ 4 12 1 13 1 , 3 ⌺ ϩ (⍀ϭ1), corroborating recent results of resonant two photon ionization spectroscopy studies. The spin-orbit interactions of these molecules are analyzed to deduce the composition of the molecular orbitals, and comparisons are made to ab initio theory when possible. An examination of the trends in bond energy, bond length, and vibrational frequency among the 4d transition metal carbides is also provided.

The bond dissociation energies D0(Al2–Al) 5 2.701(5), D0(TiO1–Mn) 5 1.7629(12), and D0(V21–V) 5 2... more The bond dissociation energies D0(Al2–Al) 5 2.701(5), D0(TiO1–Mn) 5 1.7629(12), and D0(V21–V) 5 2.323(1) eV have been measured from the sudden onset of predissociation in the photodissociation spectra of Al3, TiOMn1, and V31. For Al3, the predissociation threshold was observed in a spectrum arising from the metastable 4A2 state (in C2v symmetry), and the value of D0(Al2–Al) 5 2.701(5) eV was obtained by adding the energy of the 4A2 state to the measured predissociation threshold. For TiOMn1, there is currently no evidence that the predissociation threshold arises from a metastable excited electronic state; nor is there evidence that dissociation at the ground separated fragment limit fails to occur. Therefore, the predissociation threshold is taken to be the bond dissociation energy for this molecule. For V31, the measured predissociation threshold occurs 0.32 eV above the collision-induced dissociation (CID) measurement. Based in part on a theoretically suggested 9A02 ground state ...

A spectroscopic study of the Rydberg states of YO accessed from particular rotational levels of t... more A spectroscopic study of the Rydberg states of YO accessed from particular rotational levels of the A 2 ⌸ 1/2 , vϭ0 state has been combined with a pulsed field ionization, zero electron kinetic energy ͑PFI-ZEKE͒ investigation. The results provide accurate values of the ionization energy of YO, ionization energy I.E.͑YO͒ϭ49 304.316͑31͒ cm Ϫ1 ͓6.112 958͑4͒ eV͔, and of the rotational constant ͑and bond length͒ of the YO ϩ cation in its X 1 ⌺ ϩ , vϭ0 ground state, B 0 ϩ ϭ0.4078(3) cm Ϫ1 ͓r 0 ϭ1.7463(6) Å͔. The improved value of I.E.͑YO͒ combined with the known ionization energy of atomic yttrium then leads to the result D 0 0 (YϪO)ϪD 0 0 (YϪO͒ϭ0.1041Ϯ0.0001 eV. Combining this result with the value of D 0 0 (Y ϩ ϪO) obtained from guided ion beam mass spectrometry yields an improved value of D 0 0 (YϪO͒ϭ7.14Ϯ0.18 eV. The PFI-ZEKE spectra display an interesting channel-coupling effect so that all rotational levels with J ϩ рJЈ(A)ϩ0.5 are observed with high intensity, where J ϩ is the angular momentum of the YO ϩ cation that is produced and JЈ(A) is the angular momentum of the A 2 ⌸ 1/2 state that is reached when the first photon is absorbed. This is thought to result from the interaction between the dipole moment of the rotating YO ϩ core and the Rydberg electron, which can induce changes in l and J ϩ subject to the dipolar coupling matrix element selection rule, ⌬J ϩ ϭϮ1, ⌬lϭϮ1. The channel-coupling mechanism also appears to induce an inverse autoionization process in which an unbound electron with a low value of l is captured either by its low-J ϩ YO ϩ cation or by a second YO ϩ cation with the same value of J ϩ. This inverse autoionization process is extremely sensitive to the electron kinetic energy, leading to narrow peaks in the PFI-ZEKE spectrum which are only slightly broader than the laser linewidth employed for this study ͑0.25 cm Ϫ1 ͒.

The Journal of Chemical Physics

The bond dissociation energies of the diatomic late transition metal borides (MB, M = Fe, Co, Ni,... more The bond dissociation energies of the diatomic late transition metal borides (MB, M = Fe, Co, Ni, Ru, Rh, Os, Ir, Pt) have been assigned from the measurement of a predissociation threshold using resonant two-photon ionization (R2PI) spectroscopy. The open d-shell configurations of the transition metal constituents in the molecules studied here lead to large M L degeneracies, resulting in a dense manifold of states near the ground separated atom limit. This high density of states causes prompt predissociation to occur as soon as the ground separated atom limit is exceeded, allowing a precise assignment of the bond dissociation energy (BDE) of the molecule. The measured predissociation thresholds give BDEs of: D 0 (FeB) = 2.43(2) eV, D 0 (CoB) = 2.954(3) eV, D 0 (NiB) = 3.431(4) eV, D 0 (RuB) = 4.815(3) eV, D 0 (RhB) =5.252(3) eV, D 0 (OsB) = 4.378(3) eV, D 0 (IrB) = 4.928(10) eV, and D 0 (PtB) = 5.235(3) eV. The gaseous enthalpies of formation at 0 K for these molecules have been derived using a thermochemical cycle that relates atomic enthalpies of formation and the BDE of the molecule, giving Δ f H 0K°(g) (FeB) = 733.6(12.2) kJ mol-1 , Δ f H 0K°(g) (CoB) = 695.1(12.2) kJ mol-1 , Δ f H 0K°(g) (NiB) = 652.1(14.7) kJ mol-1 , Δ f H 0K°(g) (RuB) = 740.2(12.7) kJ mol-1 , Δ f H 0K°(g) (RhB) = 600.1(12.7) kJ mol-1 , Δ f H 0K°(g) (OsB) = 921.7(13.6) kJ mol-1 , Δ f H 0K°(g) (IrB) = 748.0(13.6) kJ mol-1 , and Δ f H 0K°(g) (PtB) = 613.9(12.2) kJ mol-1. This work reports the first experimental measurements of the BDEs of FeB, CoB, NiB, and OsB. Periodic trends are discussed.

The Journal of Chemical Physics

Predissociation thresholds of the ScSi, YSi, LaSi, ScC, YC, LaC, CoC, and YCH molecules have been... more Predissociation thresholds of the ScSi, YSi, LaSi, ScC, YC, LaC, CoC, and YCH molecules have been measured using resonant two-photon ionization spectroscopy. It is argued that the dense manifold of electronic states present in these molecules causes prompt dissociation when the bond dissociation energy (BDE) is exceeded, allowing their respective predissociation thresholds to provide precise values of their bond energies. The BDEs were measured as 2.015(3) eV (ScSi), 2.450(2) eV (YSi), 2.891(5) eV (LaSi), 3.042(10) eV (ScC), 3.420(3) eV (YC), 4.718(4) eV (LaC), 3.899(13) eV (CoC), and 4.102(3) eV (Y-CH). Using thermochemical cycles, the enthalpies of formation, Δ f H 0K°(g), were calculated as 627.4(9.0) kJ mol-1 (ScSi), 633.1(9.0) kJ mol-1 (YSi), 598.1(9.0) kJ mol-1 (LaSi), 793.8(4.3) kJ mol-1 (ScC), 805.0(4.2) kJ mol-1 (YC), 687.3(4.2) kJ mol-1 (LaC), 760.1(2.5) kJ mol-1 (CoC), and 620.8(4.2) kJ mol-1 (YCH). Using data for the BDEs of the corresponding cations allows ionization energies to be obtained through thermochemical cycles as 6.07(11) eV (ScSi), 6.15(13) eV (YSi), 5.60(10) eV (LaSi), 6.26(6) eV (ScC), 6.73(12) or 5.72(11) eV (YC, depending on the value of D 0 (Y +-C) employed), and 5.88(35) eV (LaC). Additionally, a new value of D 0 (Co +-C) = 4.045(13) eV was obtained based on the present work and the previously determined ionization energy of CoC. An ionization onset threshold allowed the measurement of the LaSi ionization energy as 5.607(10) eV, in excellent agreement with a prediction based on a thermochemical cycle. Chemical bonding trends are also discussed. including VC, VN, and VS; 1 the group 4 and 5 carbides, 2 silicides, 3 and selenides; 4 WC, WSi, WS, WSe, and WCl; 5 FeC, FeS, FeSe, NiC, NiS, and NiSe; 6 and the late (group 8-10) transition metal silicides. 7 This work is summarized in a recent review. 8 The M-C and M-Si bonds are of wide interest, with the transition metal-carbon bond being particularly important in hardening metal alloys, 9 in polymerization catalysis, 10 and in organometallic chemistry. 11, 12 Transition metal silicides are of interest primarily for their use and potential use in solid state devices, particularly as these shrink further into the nanoscale. 13 Some transition metal silicides are also of interest from geological and astrochemical perspectives. 14, 15 The molecules in this work have previously been studied by Knudsen effusion mass spectrometry, 16-21 laser induced fluorescence (LIF) spectroscopy, 22, 23 pulsed field ionization-zero electron kinetic energy (PFI-ZEKE) spectroscopy, 24 dissociation studies on the corresponding mass-selected cations, 25-30 and various computational approaches. 31-43 Studies of these systems are also important for the precise benchmarks they can provide for computational chemistry, as the open d-shell systems lead to a large number of lowlying electronic states, posing serious challenges for quantum chemical approaches. 39 Putting aside the inherent computational difficulties of the transition metal molecules, a second challenge is that for many species the available experimental data is not sufficiently precise for use as computational benchmarks. A general rule is that a calculated result within 1 kcal/mol of the experimentally determined value is considered chemically accurate. 44 Calculations involving transition metals are often held to a lower 3 kcal/mol standard, 44 although it is possible to reach the higher 1 1.01-3.82 Wide range of DFT studies Goel & Masunov 60 2 Π 3/2 LIF spectroscopy Chen, Merer, & Hsu 23 YC 3.420(3) Threshold This work 4.3(7) Pauling model prediction Gingerich 34 4 Π 4.29(15)/2.97 Knudsen effusion/CASSCF Shim, Pelino, & Gingerich 19 4.44(21) Knudsen effusion Pelino & Gingerich 20 4 Π 5/2 LIF spectroscopy Simard, Hackett, & Balfour 22 4 Π 3.35 B3LYP/LANL2DZ+6-311++G(df) Wang et al. 38 4 Σ-3.38 MRSDCI+Q Suo & Balasubramanian 39 LaC 4.718(4) Threshold This work 5.2(7) Pauling model prediction Gingerich 34 4.75(21) Knudsen effusion Pelino & Gingerich 21 2 Σ + 3.90 B3LYP/LANL2DZ+6-311++G(df) Wang et al.

The Journal of chemical physics, Jan 28, 2018

Sharp predissociation thresholds have been observed in the resonant two-photon ionization spectra... more Sharp predissociation thresholds have been observed in the resonant two-photon ionization spectra of TiC, ZrC, HfC, ThC, NbC, and TaC. Because of the large density of states in these species, particularly near the ground separated atom limit, we argue that the sharp predissociation threshold occurs at the thermochemical bond dissociation energy. The bond dissociation energies, D(MC), measured are 3.857(4) eV (TiC), 4.892(10) eV (ZrC), 4.426(3) eV (HfC), 5.060(3) eV (ThC), 5.620(4) eV (NbC), and 4.975(3) eV (TaC). Using atomic enthalpies of formation, the diatomic enthalpies of formation, ΔH(MC(g)), were also calculated as 810.0(16.7) kJ mol (TiC), 847.9(8.5) kJ mol (ZrC), 902.1(6.3) kJ mol (HfC), 825.0(6.0) kJ mol (ThC), 898.8(8.0) kJ mol (NbC), and 1012.6(2.2) kJ mol (TaC). Combining our D(MC) values with accurate values of the ionization energies of MC and M, we also report precise values of D(Ti-C) = 4.089(4) eV, D(V-C) = 3.724(3) eV, and D(Nb-C) = 5.390(4) eV. Combining the pres...

The journal of physical chemistry. A, Jan 14, 2017

Resonant two-photon ionization spectroscopy was used to locate predissociation thresholds in WC, ... more Resonant two-photon ionization spectroscopy was used to locate predissociation thresholds in WC, WSi, WS, WSe, and WCl, allowing bond dissociation energies to be measured for these species. Because of the high degree of vibronic congestion in the observed spectra, it is thought that the molecules dissociate as soon as the lowest separated atom limit is exceeded. From the observed predissociation thresholds, dissociation energies are assigned as D0(WC) = 5.289(8) eV, D0(WSi) = 3.103(10) eV, D0(WS) = 4.935(3) eV, D0(WSe) = 4.333(6) eV, and D0(WCl) = 3.818(6) eV. These results are combined with other data to obtain the ionization energy IE(WC) = 8.39(9) eV and the anionic bond dissociation energies of D0(W-C-) = 6.181(17) eV, D0(W--C) = 7.363(19) eV, D0(W-Si-) ≤ 3.44(4) eV, and D0(W--Si) ≤ 4.01(4) eV. Combination of the D0(WX) values with atomic enthalpies of formation also provides ΔfH0K° values for the gaseous WX molecules. Computational results are also provided, which shed some lig...

The Journal of Physical Chemistry

... Figure 1 shows a selected portion of the time-of-flight mass spectra for niobium clusters rea... more ... Figure 1 shows a selected portion of the time-of-flight mass spectra for niobium clusters reacting with nitrogen. The figure shows both a control mass spectrum, where (42) Bond, G. C. Catalysis by Metals; Academic Press: London, 1962. ...

The Journal of chemical physics, Jan 28, 2017

Predissociation thresholds have been observed in the resonant two-photon ionization spectra of Ti... more Predissociation thresholds have been observed in the resonant two-photon ionization spectra of TiSi, ZrSi, HfSi, VSi, NbSi, and TaSi. It is argued that because of the high density of electronic states at the ground separated atom limit in these molecules, the predissociation threshold in each case corresponds to the thermochemical bond dissociation energy. The resulting bond dissociation energies are D0(TiSi) = 2.201(3) eV, D0(ZrSi) = 2.950(3) eV, D0(HfSi) = 2.871(3) eV, D0(VSi) = 2.234(3) eV, D0(NbSi) = 3.080(3) eV, and D0(TaSi) = 2.999(3) eV. The enthalpies of formation were also calculated as Δf,0KH°(TiSi(g)) = 705(19) kJ mol(-1), Δf,0KH°(ZrSi(g)) = 770(12) kJ mol(-1), Δf,0KH°(HfSi(g)) = 787(10) kJ mol(-1), Δf,0KH°(VSi(g)) = 743(11) kJ mol(-1), Δf,0KH°(NbSi(g)) = 879(11) kJ mol(-1), and Δf,0KH°(TaSi(g)) = 938(8) kJ mol(-1). Using thermochemical cycles, ionization energies of IE(TiSi) = 6.49(17) eV and IE(VSi) = 6.61(15) eV and bond dissociation energies of the ZrSi(-) and NbSi(-)...

The Journal of chemical physics, Jan 7, 2016

Predissociation thresholds have been observed in the resonant two-photon ionization spectra of Ti... more Predissociation thresholds have been observed in the resonant two-photon ionization spectra of TiSe, ZrSe, HfSe, VSe, NbSe, and TaSe. It is argued that the sharp onset of predissociation corresponds to the bond dissociation energy in each of these molecules due to their high density of states as the ground separated atom limit is approached. The bond dissociation energies obtained are D0(TiSe) = 3.998(6) eV, D0(ZrSe) = 4.902(3) eV, D0(HfSe) = 5.154(4) eV, D0(VSe) = 3.884(3) eV, D0(NbSe) = 4.834(3) eV, and D0(TaSe) = 4.705(3) eV. Using these dissociation energies, the enthalpies of formation were found to be Δf,0KH(o)(TiSe(g)) = 320.6 ± 16.8 kJ mol(-1), Δf,0KH(o)(ZrSe(g)) = 371.1 ± 8.5 kJ mol(-1), Δf,0KH(o)(HfSe(g)) = 356.1 ± 6.5 kJ mol(-1), Δf,0KH(o)(VSe(g)) = 372.9 ± 8.1 kJ mol(-1), Δf,0KH(o)(NbSe(g)) = 498.9 ± 8.1 kJ mol(-1), and Δf,0KH(o)(TaSe(g)) = 562.9 ± 1.5 kJ mol(-1). Comparisons are made to previous work, when available. Also reported are calculated ground state electronic ...

The Journal of chemical physics, Jan 14, 2017

The bond dissociation energies of FeC, NiC, FeS, NiS, FeSe, and NiSe have been measured by the ob... more The bond dissociation energies of FeC, NiC, FeS, NiS, FeSe, and NiSe have been measured by the observation of a predissociation threshold in their resonant two-photon ionization spectra. Because the lowest separated atom limits generate a vast number of potential energy curves, it is thought that the molecules dissociate as soon as the ground separated atom limit is exceeded in energy. From the observed thresholds, dissociation energies have been measured as D0(FeC) = 3.961(19), D0(NiC) = 4.167(3), D0(FeS) = 3.240(3), D0(NiS) = 3.651(3), D0(FeSe) = 2.739(6), and D0(NiSe) = 3.218(3) eV. Through the use of thermochemical cycles, these values have been combined with other precisely known values to improve the accuracy of other quantities, providing: D0(Fe(+)-C) = 4.270(19) eV, D0(Ni(+)-C) = 3.435(3) eV, IE(FeS) = 8.06(4) eV, IE(NiS) = 8.82(4) eV, and D0 (Fe-S(-)) = 2.92(10) or 2.89(10) eV, depending on the reference employed for EA(FeS(-)). Comparisons to previous values are noted, whe...

Proceedings of the 2021 International Symposium on Molecular Spectroscopy, 2021

Journal of Physical Chemistry A, Mar 12, 2013

The Journal of Chemical Physics, 1998

The Journal of Chemical Physics, 1993

The Journal of Chemical Physics, 1998

The Journal of Chemical Physics

The Journal of Chemical Physics, 2001

The Journal of Chemical Physics

The Journal of chemical physics, Jan 28, 2018

The journal of physical chemistry. A, Jan 14, 2017

The Journal of Physical Chemistry

The Journal of chemical physics, Jan 28, 2017

The Journal of chemical physics, Jan 7, 2016

Predissociation thresholds have been observed in the resonant two-photon ionization spectra of Ti... more Predissociation thresholds have been observed in the resonant two-photon ionization spectra of TiSe, ZrSe, HfSe, VSe, NbSe, and TaSe. It is argued that the sharp onset of predissociation corresponds to the bond dissociation energy in each of these molecules due to their high density of states as the ground separated atom limit is approached. The bond dissociation energies obtained are D0(TiSe) = 3.998(6) eV, D0(ZrSe) = 4.902(3) eV, D0(HfSe) = 5.154(4) eV, D0(VSe) = 3.884(3) eV, D0(NbSe) = 4.834(3) eV, and D0(TaSe) = 4.705(3) eV. Using these dissociation energies, the enthalpies of formation were found to be Δf,0KH(o)(TiSe(g)) = 320.6 ± 16.8 kJ mol(-1), Δf,0KH(o)(ZrSe(g)) = 371.1 ± 8.5 kJ mol(-1), Δf,0KH(o)(HfSe(g)) = 356.1 ± 6.5 kJ mol(-1), Δf,0KH(o)(VSe(g)) = 372.9 ± 8.1 kJ mol(-1), Δf,0KH(o)(NbSe(g)) = 498.9 ± 8.1 kJ mol(-1), and Δf,0KH(o)(TaSe(g)) = 562.9 ± 1.5 kJ mol(-1). Comparisons are made to previous work, when available. Also reported are calculated ground state electronic ...

The Journal of chemical physics, Jan 14, 2017