“…The presence of the ballistic component implies that some molecules are coming from deeper within the matrix. Preliminary results with benzene molecules sandwiched between an sBA layer and the Ag(111) surface show this to be the case as well . However, as these molecules are in the process of desorbing, collisions with other molecules remove some of the molecules' kinetic energy.…”
Section: Resultsmentioning
confidence: 89%
“…The peaks labeled as (∼259.0 nm) and (∼266.8 nm) mark the transitions of interest. Ground-state benzene molecules (C 6 H 6 ) are ionized by first pumping the transition originating from the zero vibrational level of the molecular ground state 15 (C 6 H 6 ) with a 259.0 nm photon and absorbing a second 259.0 nm photon provides the ionization. , Vibrationally excited benzene molecules (C 6 H 6 *) are ionized by first pumping the transition starting from the first vibrationally excited state of the mode, lying ∼0.1 eV above the molecular ground-state level, with a 266.8 nm photon and absorbing a second photon (266.8 nm) produces the ionization. , The notation of C 6 H 6 and of C 6 H 6 * shall be reserved for the two particular quantum states discussed above. 2 Ultraviolet multilphoton ionization spectra of (A) benzene and (B) phenol vapor.…”
Section: Methodsmentioning
confidence: 99%
“…Such control is critical for isolating various phenomena and for providing experimental systems that may be accurately modeled. Finally, the ultraviolet spectroscopy of benzene is well documented , and experimentally accessible. , …”
Section: Introductionmentioning
confidence: 99%
“…In high-exposure systems, the molecules are desorbed with less kinetic energy as a result of localized heating . More recently, we have shown that benzene molecules can be photoionized with resonance-enhanced laser-based schemes that allow for quantum-state-resolved detection. , Obtaining quantum-state-resolved distributions of benzene molecules desorbed in the molecular ground state and in a vibrationally excited state allows us to explore in greater detail how the kinetic energy of the primary ion is distributed in the target material, permitting molecular ejection rather than fragmentation.…”
Section: Introductionmentioning
confidence: 99%
“…Finally, the ultraviolet spectroscopy of benzene is well documented 15,16 and experimentally accessible. 17,18 Previously, desorption of benzene molecules from the C 6 H 6 / Ag(111) system has been studied experimentally 13 and with MD computer simulations. 19 The experiments, which utilize a nonresonant ionization scheme for detecting benzene molecules, illustrate that the desorption mechanism switches as benzene exposure is increased.…”
We have conducted an experimental investigation into molecular desorption stimulated by 8 keV Ar + ions. The investigated systems are comprised of aromatic molecules (benzene and phenol) adsorbed to an Ag(111) surface. Resonance-enhanced laser ionization coupled with time-of-flight mass spectrometry provide the ability to obtain quantum state resolved kinetic energy distributions of the desorbed molecules. Our results indicate that the desorption mechanisms for the molecules are dictated by the molecular coverage and determine if the molecules are desorbed in an internally excited state. We use specific mechanisms observed in molecular dynamics simulations reported in the literature to describe our experimental observations. In the low coverage regime, ballistic collisions between dislocated silver substrate atoms and the adsorbed molecules lead to the emission of energetic molecules. A collision between a single substrate atom and an adsorbed molecule leads to the emission of translationally and internally hotter molecules. A collision between an adsorbed molecule and several substrate atoms with similar momentum leads to the emission of slower, internally cooler molecules. In multilayer systems, a gentler mechanism, such as a molecular collision cascade or localized heating, generates the emission of translationally slow molecules. Temperature-programmed desorption studies allow characterization of the benzene film structure and show how the emission characteristics of the desorbed molecules change concomitantly with changes in the film structure. In general, we provide a framework describing the collision events responsible for stimulated molecular desorption.
“…The presence of the ballistic component implies that some molecules are coming from deeper within the matrix. Preliminary results with benzene molecules sandwiched between an sBA layer and the Ag(111) surface show this to be the case as well . However, as these molecules are in the process of desorbing, collisions with other molecules remove some of the molecules' kinetic energy.…”
Section: Resultsmentioning
confidence: 89%
“…The peaks labeled as (∼259.0 nm) and (∼266.8 nm) mark the transitions of interest. Ground-state benzene molecules (C 6 H 6 ) are ionized by first pumping the transition originating from the zero vibrational level of the molecular ground state 15 (C 6 H 6 ) with a 259.0 nm photon and absorbing a second 259.0 nm photon provides the ionization. , Vibrationally excited benzene molecules (C 6 H 6 *) are ionized by first pumping the transition starting from the first vibrationally excited state of the mode, lying ∼0.1 eV above the molecular ground-state level, with a 266.8 nm photon and absorbing a second photon (266.8 nm) produces the ionization. , The notation of C 6 H 6 and of C 6 H 6 * shall be reserved for the two particular quantum states discussed above. 2 Ultraviolet multilphoton ionization spectra of (A) benzene and (B) phenol vapor.…”
Section: Methodsmentioning
confidence: 99%
“…Such control is critical for isolating various phenomena and for providing experimental systems that may be accurately modeled. Finally, the ultraviolet spectroscopy of benzene is well documented , and experimentally accessible. , …”
Section: Introductionmentioning
confidence: 99%
“…In high-exposure systems, the molecules are desorbed with less kinetic energy as a result of localized heating . More recently, we have shown that benzene molecules can be photoionized with resonance-enhanced laser-based schemes that allow for quantum-state-resolved detection. , Obtaining quantum-state-resolved distributions of benzene molecules desorbed in the molecular ground state and in a vibrationally excited state allows us to explore in greater detail how the kinetic energy of the primary ion is distributed in the target material, permitting molecular ejection rather than fragmentation.…”
Section: Introductionmentioning
confidence: 99%
“…Finally, the ultraviolet spectroscopy of benzene is well documented 15,16 and experimentally accessible. 17,18 Previously, desorption of benzene molecules from the C 6 H 6 / Ag(111) system has been studied experimentally 13 and with MD computer simulations. 19 The experiments, which utilize a nonresonant ionization scheme for detecting benzene molecules, illustrate that the desorption mechanism switches as benzene exposure is increased.…”
We have conducted an experimental investigation into molecular desorption stimulated by 8 keV Ar + ions. The investigated systems are comprised of aromatic molecules (benzene and phenol) adsorbed to an Ag(111) surface. Resonance-enhanced laser ionization coupled with time-of-flight mass spectrometry provide the ability to obtain quantum state resolved kinetic energy distributions of the desorbed molecules. Our results indicate that the desorption mechanisms for the molecules are dictated by the molecular coverage and determine if the molecules are desorbed in an internally excited state. We use specific mechanisms observed in molecular dynamics simulations reported in the literature to describe our experimental observations. In the low coverage regime, ballistic collisions between dislocated silver substrate atoms and the adsorbed molecules lead to the emission of energetic molecules. A collision between a single substrate atom and an adsorbed molecule leads to the emission of translationally and internally hotter molecules. A collision between an adsorbed molecule and several substrate atoms with similar momentum leads to the emission of slower, internally cooler molecules. In multilayer systems, a gentler mechanism, such as a molecular collision cascade or localized heating, generates the emission of translationally slow molecules. Temperature-programmed desorption studies allow characterization of the benzene film structure and show how the emission characteristics of the desorbed molecules change concomitantly with changes in the film structure. In general, we provide a framework describing the collision events responsible for stimulated molecular desorption.
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