Evaporation and scattering of neon, methane, and water from a dodecane flat liquid jet

Abstract

The evaporation and scattering of Ne, CD4, and D2O from a dodecane flat liquid jet are investigated in a molecular beam apparatus. The experiment yields translational energy distributions as a function of scattering angle by means of a rotatable mass spectrometer. In the evaporation experiments, one observes a Maxwell–Boltzmann distribution with a cos θ angular distribution superimposed on a weak, isotropic background. The scattering experiments show contributions from impulsive scattering and thermal desorption. At select incident angles for the three systems, angular distributions show super-specular scattering for the impulsive scattering channel, an effect attributed to anisotropic momentum transfer to the liquid surface. The impulsive scattering channel is analyzed with a soft-sphere model to explore energy transfer between the scatterer and liquid as a function of deflection angle. Compared to Ne scattering, the polyatomic gases exhibit more thermal desorption and, in the impulsive scattering channel, a higher degree of internal excitation.

Extreme ultraviolet time-resolved photoelectron spectroscopy of adenine, adenosine and adenosine monophosphate in a liquid flat jet

“…This device has been used by our group in molecular beam scattering experiments where a flat jet is formed by flowing liquid through the two outer channels; the central channel is not used. 72,73 The flat jet thus produced in so-called “colliding-jet” geometry has been used in XUV photoelectron spectroscopy by Winter 74 and Suzuki. 75 In our TRPES experiment, we operate the flat jet in the “gas dynamic” mode, in which liquid flows through the central channel and He gas flows through the two outer channels, flattening the liquid jet and producing the image in Fig.…”

Energy- and Angle-Resolved Scattering of Ne from Dodecane Liquid Surfaces: Theory Corroborating Experiment

“…The TD fraction as a function of deflection angle χ was also available from experiment. 13 Figure 3b compares our simulated results to the experiment at an incidence angle θ i of 60°. Clearly, as χ increases, the Ne atoms are scattered closer to the surface normal.…”

“…Although cylindrical microjets are amenable to volatile liquids, they provide only a small scattering target, not ideal for accurate measurement of the scattering angle, one of the most important gas−liquid dynamic observables. 12,13 In addition, many previous gas−liquid scattering experiments reported incomplete information about the scattering, due to instrumentation design. 14−16 For example, Ne scattering from neat squalene and dodecane liquid surfaces has been investigated using a wetted wheel 14 and/or cylindric microjet 16 with incidence energies (denoted as E i ) at 6−75 kJ/mol.…”

“…4 Very recently, the Neumark group developed a new experimental setup with a microfluidic chip for generating a stable flat liquid jet and investigated scattering dynamics of Ne (and several small molecules) from a pure dodecane liquid surface. 12,13 This new instrument should be more suitable for volatile liquids than the wetted wheel approach 10 and capable of providing a larger and more well-defined scattering target for detecting the scattered atoms and molecules than cylindrical liquid jets. 11 The Neumark group utilized this advanced experimental technique to measure both angle-and energyresolved dynamic properties for Ne evaporation and Ne scattering from a pure dodecane surface, with unprecedented detail.…”

“…The overall distribution of translational energy exhibits a single peak, consistent with the experimental TOF spectra. 12,13 The fractional energy loss, defined as ΔE/E i , where ΔE = E i − ⟨E IS ⟩, is commonly used to quantify the kinetic energy transferred from the impinging molecule to the liquid. 7,24 Here, ⟨E IS ⟩ denotes the average final translational energy of scattered Ne atoms in the IS channel.…”