Electron affinity and excited states of methylglyoxal

Abstract

Using photoelectron imaging spectroscopy, we characterized the anion of methylglyoxal (XA″ electronic state) and three lowest electronic states of the neutral methylglyoxal molecule: the closed-shell singlet ground state (XA'), the lowest triplet state (aA″), and the open-shell singlet state (AA″). The adiabatic electron affinity (EA) of the ground state, EA(XA') = 0.87(1) eV, spectroscopically determined for the first time, compares to 1.10(2) eV for unsubstituted glyoxal. The EAs (adiabatic attachment energies) of two excited states of methylglyoxal were also determined: EA(aA″) = 3.27(2) eV and EA(AA″) = 3.614(9) eV. The photodetachment of the anion to each of these two states produces the neutral species near the respective structural equilibria; hence, the aA″ ← XA″ and AA″ ← XA″ photodetachment transitions are dominated by intense peaks at their respective origins. The lowest-energy photodetachment transition, on the other hand, involves significant geometry relaxation in the XA' state, which corresponds to a 60° internal rotation of the methyl group, compared to the anion structure. Accordingly, the XA' ← XA″ transition is characterized as a broad, congested band, whose vertical detachment energy, VDE = 1.20(4) eV, significantly exceeds the adiabatic EA. The experimental results are in excellent agreement with the ab initio predictions using several equation-of-motion methodologies, combined with coupled-cluster theory.

Electron Attachment Reaction Ionization of Gas-Phase Methylglyoxal

“…The sharp band at binding energy of 0.91 eV (Figure 3c) can be assigned as the EA defining transition, which is consistent with the EA of MGLY (0.87 ± 0.01 eV) reported by Sanov and co-workers. 52 Slightly above the EA defining band, a broad band above 1.0 eV was observed, which is consistent with the reported photoelectron spectrum of MGLY − . 52 The Franck−Condon (FC) simulations were used to further verify the geometric and electronic structures of MGLY − .…”

“…52 Slightly above the EA defining band, a broad band above 1.0 eV was observed, which is consistent with the reported photoelectron spectrum of MGLY − . 52 The Franck−Condon (FC) simulations were used to further verify the geometric and electronic structures of MGLY − . The convolution resolution of 30 meV 58 and the temperature of 10 K were applied to obtain the simulated spectrum.…”

“…The electron affinity (EA) of Au is reported to be 2.309 eV. 61 The reaction of charge transfer from Au − to MGLY (EA = 0.87 eV 52 ) is impossible since it is endothermic (Au − + MGLY → Au + MGLY − , ΔH = +1.44 eV). We propose that EAR occurs between MGLY and lowenergy electrons produced by laser ablation of the metal disk (Au).…”

“…For example, the EAD channels and rate constants of a series of nitrobenzene compounds 49 and halogenated hydrocarbons 50,51 were investigated. Inspired by these studies and considering the high electron affinity energy of MGLY (0.87 ± 0.01 eV 52 ), we render that the EAR may be used for MGLY detection.…”

Analisis Molekular dan Transpor Ion Amonium Clorida

“…Klorin berwujud gas yang berwarna kuning-hijau pada suhu kamar. Klor merupakan elemen sangat reaktif dan oksidator kuat, mempunyai afinitas elektron (84)(85)(86)(87)(88)(89) , tertinggi dan elektronegativitas (84)(85)(86)(87) tinggi ke-3 setelah oksigen (90)(91)(92)(93)(94)(95)(96)(97) dan fluor.…”