Photoionization of HOCO revisited: a new upper limit to the adiabatic ionization energy and lower limit to the enthalpy of formation

• Published in: Chemical physics letters Vol. 316; no. 1; pp. 45 - 50
• Main Authors: Ruscic, Branko, Litorja, Maritoni
• Format: Journal Article
• Language: English
• Published: United States Elsevier B.V 07.01.2000
• Subjects: EXCITATION; FORMATION HEAT; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; IONIZATION; LIMITING VALUES; PHOTOIONIZATION; RADICALS
• ISSN: 0009-2614; 1873-4448
• DOI: 10.1016/S0009-2614(99)01267-1

A new upper limit to the adiabatic ionization energy of trans-hydroxyoxomethyl, EI( t-HOCO)≤8.195±0.022 eV, is provided, producing a lower limit to the enthalpy of formation, Δ H f 0 o( t-HOCO)≥−45.8±0.7 kcal/mol (≥−46.5±0.7 kcal/mol at 298 K). The spectrum shows progressions in CO and C–O stretches of HOCO + and provides evidence for the excitation of OCO bend. In addition, the data tentatively suggest an ionization onset as low as 8.06±0.03 eV. While it is not clear whether the latter corresponds to cis or trans isomer, it may indicate that Δ H f 0 o(HOCO) is even higher.