State-selected imaging studies of formic acid photodissociation dynamics

Abstract

The photodissociation dynamics of formic acid have been studied using the velocity map ion imaging at the UV region. The measurements were made with resonance enhancement multiphoton ionization (REMPI) spectroscopy and dc slicing ion imaging. The OH REMPI spectrum from the photodissociation of formic acid at 244 nm has been recorded. The spectrum shows low rotational excitation (N<or=4). By fixing the probe laser at the specific rotational transitions, the resulting OH images from various dissociation wavelengths have been accumulated. The translational energy distributions derived from the OH images imply that about half of the available energies go to the photofragments internal excitation. The dissociation dynamics of formic acid were also discussed in view of the recent theoretical calculations.

Roaming Dynamics and Conformational Memory in Photolysis of Formic Acid at 193 nm Using Time-resolved Fourier-transform Infrared Emission Spectroscopy

“…In addition, upon irradiation of 193 nm, the C=O bond in HCOOH is elongated significantly. Following dissociation to form HCO and OH radicals, most internal energy carried by HCO is favorably deposited in the CO vibrational stretching 40 . The OH-roaming around the HCO core thus Fig.…”

“…As an example using carbonyl compounds in the photodissociation, aliphatic aldehydes showed a loose roaming saddle point along the roaming dissociation coordinate 26,27 , whereas the roaming signature in methyl formate (HCOOCH 3 ) was verified to involve multiple energy states via a conical intersection 17,18 . These two types of roaming dynamics apparently behave differently.Formic acid (HCOOH) belongs to the family of carbonyl compounds, and its photodissociation dynamics has been popularly investigated for more than two decades [28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43] . When its electronic band S 1 in the range 220 ∼ 250 nm is excited, the dissociation channel mainly contains HCO + OH with a quantum yield of 0.7∼0.8 30 .…”

Safety Assessment of Formic Acid and Sodium Formate as Used in Cosmetics

“…64-18-6), the simplest carboxylic acid, having just 1 carbon, is a volatile (vapor pressure is 42.71 hPa), weak (pKa 3.7) organic acid. 2,7 Sodium formate (CAS No. 141-53-7) is the sodium salt of formic acid.…”

“…According to information supplied to the FDA VCRP in 2013, formic acid and sodium formate were being used in 31 and 9 cosmetic products, respectively. 7 These data are summarized in Table 1. Results from a survey of ingredient use concentrations provided by the Council (also included in Table 1) in 2012 indicate that formic acid and sodium formate were being used at concentrations up to 0.2% and 0.34%, respectively, with hair care products accounting for the highest use concentrations of both ingredients.…”

Inhibit the formation of toxic methylphenolic by-products in photo-decomposition of formaldehyde–toluene/xylene mixtures by Pd cocatalyst on TiO2

“…Mechanistic studies reveal that photo-dissociation of formaldehyde either undergoes direct oxidation to CO2 or proceeds via an indirect route with formic acid as the intermediate [20,29]. Noticeably, the presence of abundant hydroxyl radicals (•OH) has been identified as the major oxidative species in both cases [30,31]. In the photo-decomposition of toluene, benzaldehyde is observed as the intermediate prior to the cracking of the aromatic ring by the superoxide radicals (•O2 ) [32,33].…”