Cross sections and NO product state distributions resulting from substrate mediated photodissociation of NO2 adsorbed on Pd(111)

Abstract

Ultraviolet irradiation of NO2 adsorbed on top of a NO saturated Pd(111) surface causes the photodissociation of NO2/N2O4 and results in the desorption of NO molecules. This process has been studied using excitation energies between 3.5 and 6.4 eV. At a photon energy of 6.4 eV, a cross section of 3×10−18 cm2 is found. Using laser-induced fluorescence to detect the desorbed NO molecules, fully state-resolved data detailing the energy channeling into different degrees of freedom has been obtained. Two desorption channels are found, one characterized by nonthermal state populations, and one showing accommodation to the surface. The yield of the fast channel shows a marked increase above 4 eV photon energy. The slow channel is interpreted as being due to NO molecules which, after formation, undergo a trapping–desorption process. A polarization experiment indicates that the photodissociation is initiated by excitation of metal electrons rather than direct absorption by the adsorbate.

Ultraviolet-laser induced desorption of NO from the Cr2O3(0001) surface: Involvement of a precursor state?

“…The phenomenon of trapping or caging prior to desorption has frequently been observed in several photodesorption experiments. [10][11][12][13] In those cases, internal state distributions after desorption normally exhibit two channels, one hot channel resulting from direct desorption and a second channel attributed to trapping with internal state distributions accommodated to the surface temperature.…”

Isotope and Quantum Effects in Vibrational State Distributions of Photodesorbed Ammonia

“…Photostimulated desorption processes have attracted considerable interest in recent years due to their fundamental importance and their ability to provide complementary insights into molecule-surface interaction dynamics [1,2]. State resolved detection of desorbed molecules and isotopic substitution of adsorbates are powerful tools in unraveling the details of the microscopic events leading eventually to photodesorption [3][4][5][6][7][8]. The photodesorption of ammonia has been proven to be a system rich in detail, since the desorption dynamics follows a path which is multidimensional in canonical coordinates [9][10][11].…”

Photodissociation dynamics of (NO)2 on LiF(001): Characterization of vibrationally excited NO fragments

“…18 The phenomenon has been explained in two separate calculations based on mechanisms of the MGR variety involving shortlived excited states 1,47,48 ͑see discussion in Sec. IV B͒.…”

“…State-selective detection methods have also been used to characterize NO fragments formed in the photodissociation of adsorbed NO 2 dimers on a NO covered Pd͑111͒ surface 18 and on LiF͑001͒. 19 Of particular interest for the present study is a work by Natzle et al 20 in which the photodissociation of ͑NO͒ 2 in multilayer films on Ag͑111͒ was characterized in the wavelength region 220-270 nm using time-of-flight mass spectrometry and REMPI.…”