Some of the trans-glyoxal vibrational and rotational levels that are accessible by inelastic collisions from , . (Left) All of the vibrational energy levels within of the zero point vibrational level. The fundamental frequencies (in ) are listed in parentheses. (Right) Some of the rotational energy levels for the zero point and vibrational levels. energies are used. The symmetric axis (the axis) is indicated on the molecule.
The distribution of the center-of-mass collision energies and momenta used in the inelastic scattering experiments. The error bars represent the distribution of kinematic values that result from the distribution of relative velocities and beam divergence. The top plot contains an enhanced view of the three lightest target gases while the bottom plot contains values for experiments behind all of the data discussed here.
(Top) A portion of the fluorescence spectrum from glyoxal molecules that were involved in an inelastic collision with at a 180° intersection angle. Each structure is from states within the zero point level populated by rotational scattering and from states within the rotational manifold reached by rovibrational scattering. The gap in the spectrum coincides with the band origin and is a result of the depopulation of the initially pumped states. The maxima to the blue of the origin are the subband heads from states populated by inelastic scattering, some of which are labeled. The band origin is at . The maxima to the blue of that origin are states populated by rovibrational scattering. (Bottom) The dotted spectrum is a simulation of the experimental spectrum (solid line) from which the relative cross sections are extracted.
The relative state-to-state cross sections extracted from simulations of experimental spectra plotted against the change in energy . The rotationally and rovibrationally inelastic cross sections are depicted as black circles and open squares, respectively.
The relative state-to-state cross sections extracted from the simulations of the experimental spectra plotted against the change in rotational quantum number . The rotationally and rovibrationally inelastic cross sections are depicted as black circles and open squares, respectively.
(Color) The slope of the rotational cross sections depicted in Fig. 5 are plotted against the experimental kinematic parameters , , and . The horizontal error bars reflect the range in the kinematic parameter due to the relative velocity spread in the molecular beams. The vertical error bars depict the uncertainty in the slope measurements. The data points include (black), He (red), (open), Ne (blue), and Ar, Kr, and Xe (green). The box in the top left plot highlights some of the slopes from , He, and that demonstrate the dominant influence of on rotational channel competition.
The fit of the AM model to the distribution of relative cross sections for the rotationally inelastic scattering of and He from glyoxal. The adjustable parameters used to generate the fit and the quality of the fit is listed at the bottom left corner of each plot.
(Color) The maximum impact parameter extracted from the AM model plotted against the three parameters , , and . The large red square in the bottom plot highlights values for collisions with , , He, and Ne that show to be strictly dependent on . The smaller black box highlights identical values obtained for the three, , He, and Ne, experiments in which kinematics were tuned to produce the same .
Plot of the change in rotational quantum number as a function of the maximum impact parameter . The solid and dashed lines represent collisions with Xe and at a 90° intersection angle, respectively. The horizontal lines indicate the maximum rotational state accessible at the collision energy of the experiment. Here the plot demonstrates that the torque arm involved in collisions with is generally much larger than that for Xe even though the accessible range is smaller.
Plots of the sum of the rotational to rovibrational cross section ratios listed in Table VI as a function of the various collision kinematic parameters.
The collision kinematic parameters for the scattering experiments of the present work.
Relative cross sections from and . The headers for each column refer to the target gas (beam intersection angle, glyoxal see gas).
Relative cross sections from . The headers for each column refer to the target gas (beam intersection angle, glyoxal seed gas).
Figure 5 slopes for the six studies of the present experiments plus those from a similar analysis for previously reported experiments (Refs. 24 and 42). Slopes are listed for data and data . The experiments listed in the first column refer to the target gas (beam intersection angle, glyoxal seed gas).
Optimum values of the adjustable parameters in AM model fits to data.
The ratio of overall rotational to rovibrational scattering as defined by the sum of cross section and with for experiments listed in Table I. The experiments listed in the first column refer to the target gas (beam intersection angle, glyoxal seed gas).
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