HCO rotational excitation in the photoinitiated unimolecular decomposition of H2CO

Collision dynamics of proton with formaldehyde: Fragmentation and ionization

“…30 Second, the proton as a single ion-projectile is favored because of its missing electronic structure and capability of capturing electrons as well as its abundance in the solar wind and in the ISM. Third, so far, a great deal of work about formaldehyde has concentrated on unimolecular photodissociation, [31][32][33][34][35][36][37][38] collision-induced ionization and dissociation by electrons, 28, 39-43 atoms, [44][45][46][47][48][49][50] and ions. [51][52][53] Unfortunately, little is known about the physical process of proton impact on formaldehyde, although Jalbout 30 advanced the study of a single formaldehyde reacting with a single proton source (H + 3 , H 3 O + ).…”

State-selective photodissociation dynamics of formaldehyde: Near threshold studies of the H+HCO product channel

“…[19][20][21] Both of these processes are thought to occur via radiationless decay from the à 1 A 2 state of formaldehyde, and both processes have been studied previously. [19][20][21] Both of these processes are thought to occur via radiationless decay from the à 1 A 2 state of formaldehyde, and both processes have been studied previously.…”

“…Although electronically forbidden, the S 1 ← S 0 transition shows a͒ Authors to whom correspondence should be addressed. 19 The spectral region between 31 000 and 33 000 cm −1 is of particular interest since the minimum energy pathway over the T 1 barrier is predicted at ϳ32 350 cm −1 . 3 S 1 → S 0 IC can yield both the H 2 +CO and H+HCO products, provided minimum threshold energy requirements are met.…”

“…3 S 1 → S 0 IC can yield both the H 2 +CO and H+HCO products, provided minimum threshold energy requirements are met. 19 With increasing energy, however, T 1 quantum state widths are expected to increase due to lifetime broadening as a result of quantum tunneling until, at energies above the T 1 barrier, S 1 -T 1 coupling occurs via the T 1 dissociation continuum. 22 As a consequence, competition between the IC and ISC HCO formation mechanisms results, wherein dissociation occurs predominantly on the S 0 PES at threshold energies, whereas at energies near ͑and above͒ the T 1 barrier dissociation could occur on S 0 and/or T 1 .…”

“…22 As a consequence, competition between the IC and ISC HCO formation mechanisms results, wherein dissociation occurs predominantly on the S 0 PES at threshold energies, whereas at energies near ͑and above͒ the T 1 barrier dissociation could occur on S 0 and/or T 1 . 19,33 For this reason, the formyl radical product pathway should evolve from an S 0 dominated dissociation mechanism at energies far below the T 1 barrier to a T 1 dominated mechanism at energies above this barrier. 19 The spectral region between 31 000 and 33 000 cm −1 is of particular interest since the minimum energy pathway over the T 1 barrier is predicted at ϳ32 350 cm −1 .…”