ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTProbing the transition state with negative ion photodetachment: chlorine atom + hydrogen chloride and bromine bromide reactionsR. B. Metz, A. Weaver, S. E. Bradforth, T. N. Kitsopoulos, D. M. NeumarkCite this: J. Phys. Chem. 1990, 94, 4, 1377–1388Publication Date (Print):February 1, 1990Publication History Published online1 May 2002Published inissue 1 February...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSpectroscopy of the iodine atom + hydrogen iodide transition-state region by photodetachment IHI-A. Weaver, R. B. Metz, S. E. Bradforth, and D. M. NeumarkCite this: J. Phys. Chem. 1988, 92, 20, 5558–5560Publication Date (Print):October 1, 1988Publication History Published online1 May 2002Published inissue 1 October 1988https://pubs.acs.org/doi/10.1021/j100331a004https://doi.org/10.1021/j100331a004research-articleACS PublicationsRequest reuse...

We have determined the branching ratio for reaction of hydrogen atoms and HOD with either O–H bond excited or O–D excited. In both cases, initially reacts preferentially. Excitation third stretching overtone, 4νOH, favors breaking by a factor ∼200, excitation fourth 5νOD, ∼220. Thus vibrational can control H+HOD to produce product almost exclusively. A simple model using calculated wave function each state measured cross section particular predicts high selectivity observed two reactions.

Photoelectron spectra of HCO−2 and DCO−2 at 299 nm, 266 213 nm are reported. Photodetachment accesses the 2A1, 2B2, 2A2 states formlyoxyl radical, HCO2. The 2A1 state is assigned as HCO2 ground state, although it nearly degenerate with 2B2 (T0=0.027 eV), lies T0=0.536 eV. electron affinity 3.498±0.015 show partially resolved vibrational features, primarily involving progressions in CO2 bending mode. irregular appearance some regions suggests vibronic coupling between states. possible role...

ADVERTISEMENT RETURN TO ISSUEPREVArticleMode- and Bond-Selective Reactions of Chlorine Atoms with Highly Vibrationally Excited H2O HODJohn D. Thoemke, Joann M. Pfeiffer, Ricardo B. Metz, F. Fleming CrimCite this: J. Phys. Chem. 1995, 99, 37, 13748–13754Publication Date (Print):September 1, 1995Publication History Published online1 May 2002Published inissue 1 September 1995https://pubs.acs.org/doi/10.1021/j100037a023https://doi.org/10.1021/j100037a023research-articleACS PublicationsRequest...

The photoelectron spectra of the ions BrHI−, ClHI−, and FHI−, along with their deuterated counterparts, are presented. These provide information on transition state region potential energy surfaces describing exothermic neutral reactions X+HI→HX+I(X=Br, Cl, F). Vibrational structure is observed in BrHI− ClHI− that corresponds to hydrogen atom motion dissociating complex. Transitions electronically excited correlate HX+I(2P3/2,2P1/2) products also observed. A one-dimensional analysis used...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSpectroscopy of the transition state: hydrogen abstraction reactions fluorineS. E. Bradforth, D. W. Arnold, R. B. Metz, A. Weaver, and M. NeumarkCite this: J. Phys. Chem. 1991, 95, 21, 8066–8078Publication Date (Print):October 1, 1991Publication History Published online1 May 2002Published inissue 1 October 1991https://pubs.acs.org/doi/10.1021/j100174a014https://doi.org/10.1021/j100174a014research-articleACS PublicationsRequest reuse...

The binding motifs of clusters Al+ and Al2+ with ethane, Alx+(C2H6)n (x = 1, 2; n 1–3), are determined using vibrational photodissociation spectroscopy in the C–H stretching region (2550–3100 cm−1) conjunction spectra calculated density functional theory. relative energies candidate structures B3LYP-D3 ωB97X-D functionals 6–311++G(d,p) basis set. Local mode Hamiltonian calculations better able to reproduce than scaled harmonic calculations, due contributions from bending overtones...

We report the bond selected photodissociation of HNCO from a vibrationally excited state containing three quanta N–H stretch (3ν1) and demonstrate that initial vibrational preparation strongly influences photochemical branching in HNCO, producing either NCO (X 2Π) cleavage or NH (a 1Δ) C–N bond. Initial excitation dissociation coordinate by stretching overtone enhances probability for breaking electronically state. Compared to isoenergetic photolysis ground state, 3ν1 alters quantum yield...

We report the first vibrationally resolved spectroscopic study of FeO+. observe 0←0 and 1←0 bands a Σ6←XΣ6 transition at 28 648.7 29 311 cm−1. Under slightly modified source conditions 1←1 is observed 473 In addition to establishing an upper limit D0o(Fe+–O)⩽342.7 kJ/mol, our results give experimental measurements vibrational frequencies in both ground state, ν0″=838±4 cm−1, excited electronic ν0′=662±2 Partially rotational structure underlying peaks has been analyzed measure predissociation...

Photoionization efficiency curves were measured for gas-phase FeO and CuO using tunable vacuum-ultraviolet radiation at the Advanced Light Source. The molecules are prepared laser ablation of a metal-oxide powder in novel high-repetition-rate source thermally moderated supersonic expansion. These measurements provide first directly ionization energy CuO, IE(CuO)=9.41±0.01eV. direct measurement also gives greatly improved FeO, IE(FeO)=8.56±0.01eV. connects dissociation energies neutral...

The spectroscopy and dissociation dynamics of the NCO radical have been investigated by applying fast beam photodissociation to B̃ 2Π←X̃ 2 Π electronic transition. Measurements cross section as a function wavelength show that even lowest vibrational levels 2Π state predissociate. Analysis fragment kinetic energy release reveals spin-forbidden N(4S)+CO(1Σ+) products are produced exclusively until 20.3 kcal/mol above origin, at which point, spin-allowed N(2D)+CO product channel becomes...

The photoelectron spectrum of the FH−2 anion is reported. provides a probe transition state region for F+H2 reaction. experimental compared to recent simulation by Zhang and Miller which assumes T5a potential energy surface substantially broader. While this may be due inaccuracies in surface, possibility additional transitions low-lying excited electronic surfaces not included must also considered.

Gas phase FeO+ can convert methane to methanol under thermal conditions. Two key intermediates of this reaction are the [HO−Fe−CH3]+ insertion intermediate and Fe+(CH3OH) exit channel complex. These selectively formed by laser-ablated Fe+ with organic precursors specific source conditions cooled in a supersonic expansion. Vibrational spectra sextet quartet states O−H C−H stretching regions measured infrared multiple photon dissociation monitoring argon atom loss following irradiation...

Solvated cluster ions Co2+(H2O)n with n = 4−7 have been generated by electrospray ionization and studied laser photofragment spectroscopy. The similarity between the spectrum of gas-phase Co2+(H2O)6 absorption aqueous cobalt(II) suggests that (aq) is responsible for room-temperature solution spectrum. observed photodissociation Co2+(H2O)4 similar to new bands which appear in at high temperatures assigned Swaddle Fabes (Swaddle, T. W.; Fabes, L. Can. J. Chem. 1980, 58, 1418−1426). hexahydrate...

In order to better characterize the transition-state region for I + HI, Br and HBr reactions, photoelectron spectra of IHI−, IDI−, BrHI−, BrHBr−, BrDBr− have been simulated using a three-dimensional adiabatic approach. This method simulation uses Born–Oppenheimer separation in time scales between fast hydrogen-atom motion slow halogen-atom greatly simplify computation spectrum. The resulting simulations are compared experimental threshold photodetachment these anions, ‘‘exact’’ IHI− IDI−...

Transition metal cations M+ and oxide MO+ can activate C–H C–C bonds in hydrocarbons. In this review, we discuss our studies of the electronic spectroscopy dissociation dynamics intermediates, reactants products these reactions using photofragment spectroscopy. Results are presented on intermediates methane activation by FeO+, as well NiO+ PtO+. Resonance enhanced photodissociation allows us to measure FeO+ below limit with rotational resolution. Complementary time-dependent B3LYP...

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Oxygen, hydrogen, and chlorine atoms react with vibrationally excited HCN to produce CN OH, H2, or HCl, respectively. The experiments presented here use direct vibrational overtone excitation prepare states of having four quanta C–H stretching [(004) state] three C≡N two [(302) laser-induced fluorescence determine the rotational product. We find that reaction O produces little energy, 85% in v=0, 12% v=1, 3% v=2. from H is slightly more energetic, 77% 17% 6% By contrast, Cl a considerable...

Photoionization efficiency curves were measured for gas-phase PtC, PtO, and PtO2 using tunable vacuum ultraviolet (VUV) radiation at the Advanced Light Source. The molecules prepared by laser ablation of a platinum tube, followed reaction with CH4 or N2O supersonic expansion. These measurements provide first directly ionization energy IE(PtC) = 9.45 +/- 0.05 eV. direct measurement also gives greatly improved energies oxides, IE(PtO) 10.0 0.1 eV IE(PtO2) 11.35 connects dissociation neutral...

The electronic spectra of Co+(H2O), Co+(HOD), and Co+(D2O) have been measured from 13 500 to 18 400 cm–1 using photodissociation spectroscopy. Transitions four excited states with vibrational partially resolved rotational structure are observed. Each transition has an extended progression in the metal–ligand stretch, v3, absolute quantum numbering is assigned by comparing isotopic shifts between Co+(H216O) Co+(H218O). For low-lying states, first observed v3′ = 1. This allows Co+–(H2O)...

We present the details of a fast ion velocity map imaging mass spectrometer that is capable photofragments trap-cooled (≥7 K) ions produced in versatile source. The new instrument has been used to study predissociation N2O+ by electric discharge and direct dissociation Al2+ formed laser ablation. instrument's resolution currently limited diameter collimating iris value Δv/v = 7.6%. Photofragment images show when predissociative state changed from 2Σ+(200) 2Σ+(300) dominant product channel...