Energy partitioning in the femtosecond-laser-induced associative D 2 desorption from Ru(0001)

摘要: Energy transfer to different degrees of freedom during the femtosecond-laser-induced recombinative desorption ${\mathrm{D}}_{2}$ from a deuterium-covered Ru(0001) surface $({\mathrm{D}}_{\mathrm{ads}}+{\mathrm{D}}_{\mathrm{ads}}∕\mathrm{Ru}\ensuremath{\rightarrow}{\mathrm{D}}_{2,\text{gas}}+\mathrm{Ru})$ has been investigated. $(1+{1}^{\ensuremath{'}})$-resonance-enhanced multiphoton photoionization (REMPI) and time-of-flight (TOF) measurements are utilized provide information on internal external (translational) energy content, respectively. Rovibrational population distributions reaction product detected via various $B\phantom{\rule{0.2em}{0ex}}^{1}\ensuremath{\Sigma}_{u}^{+}\ensuremath{\leftarrow}X\phantom{\rule{0.2em}{0ex}}^{1}\ensuremath{\Sigma}_{g}^{+}$ Lyman bands using tunable vacuum ultraviolet laser radiation in resonant excitation step. Rotational quantum state populations vibrational ground first excited measured yielding average rotational energies $⟨{E}_{\mathrm{rot}}⟩∕{k}_{\mathrm{B}}=800$ $1500\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, respectively, for an absorbed fluence $⟨F⟩$ $85\phantom{\rule{0.3em}{0ex}}\mathrm{J}∕{\mathrm{m}}^{2}$. In addition, mean desorbing molecules is extracted which amounts $⟨{E}_{\mathrm{vib}}⟩∕{k}_{\mathrm{B}}=1200\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. Extensive TOF enable complete balancing with $⟨{E}_{\mathrm{trans}}⟩∕2{k}_{\mathrm{B}}=2500\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ at $⟨F⟩=85\phantom{\rule{0.3em}{0ex}}\mathrm{J}∕{\mathrm{m}}^{2}$ underline nonthermal unequal partitioning between within product. The effects multidimensional electronic friction substrate adsorbate layer peculiarities potential landscape governing recombination discussed.