Photodissociation of Nitrous Oxide Revisited by High-Resolution Photofragment Imaging:  Energy Partitioning

Abstract

Energy partitioning in the 203-205 nm photodissociation of N 2 O was studied by velocity map ion imaging of O( 1 D 2 ) and (2+1) resonance-enhanced multiphoton ionization (REMPI) of N 2 (X 1 ∑ g + ) via the a′′( 1 ∑ g + ) state. The observed translational energy distribution of O atoms exhibited a discrete structure due to quantized rotational energies of the counterpart N 2 fragments. The maximum of the N 2 rotational distribution has shifted from J ) 72 to 74 in changing the photodissociation wavelength from 205.5 to 203.8 nm. Comparison of the translational energy distribution of O( 1 D 2 ) with the REMPI spectrum of N 2 (X 1 ∑ g + ) revealed that the REMPI intensities of N 2 via particular rotational levels in the a′′ state were specifically reduced. These rotational levels exhibited energy shifts due to perturbation, indicating that the REMPI efficiency is reduced by the interactions between the a′′ state and other valence electronic state(s).

Single-field slice-imaging with a movable repeller: Photodissociation of N2O from a hot nozzle

“…As observed previously, [14][15][16][17][18][19][20][21][22] Since the corresponding sibling N 2 (J) photofragments do not show this effect, e.g., in Fig. 6 the angular distribution is maximum at θ = 0 o , this has been attributed to a preferential alignment of the O( 1 D 2 ) atomic orbital with respect to the recoil velocity.…”

“…Also due to the large change in NNO angle upon photoexcitation, N 2 photoproducts are formed with a large amount of rotational excitation (60 < J < 80). In recent years N 2 O has been subject to a number of high resolution experiments [13][14][15][16] using VMI, [17][18][19][20][21][22] as well as high level theoretical calculations. [23][24][25][26][27][28][29][30][31][32] In the most recent VMI study of Suzuki and coworkers, 22 the authors ionized individual rotational states of the N 2 photoproduct.…”

Photodissociation of N2O: Energy partitioning

“…Similar experiments were reported by Neyer et al 11 and Nishidi and Suzuki. 13 The maximum intensity was measured for n = 0 and j = 74 in all experiments. The spectra for j ≤ 74 look regular and the determination of rotational state distributions is straightforward.…”

“…The partitioning of the available energy into translational, vibrational, and rotational energy has been investigated in several laboratories using different methods. [8][9][10][11][12][13][14] The angular distribution of the products has also been studied intensively. 11,14 A realistic description of the photofragmentation process requires accurate potential energy surfaces (PESs).…”

Near ultraviolet photochemistry of 2-bromo- and 2-iodothiophene: Revealing photoinduced ring opening in the gas phase?

“…As with several other reported spectrometer designs, [30][31][32][33][34][35][36] the ion optics assembly described in Ref. 25 provided a convenient starting point.…”