Kinematic broadening

The determination of Eo from visible onsets introduces considerable error in the derived bond dissociation energies. This problem is primarily attributed to experimental kinematic broadening introduced through the ion beam energy distributions and the thermal motion of the target gas in the case of beam cell experiments. Armentrout et have fit various functional... 

The thermal motion of the atoms in the source volume leads to a broadening of the observed line, because the thermal velocity vth of the electron-emitting atom is added to the electron velocity v0. For an estimation of the resulting disturbance by this kinematical effect it is sufficient to select for the thermal velocity the two directions at which the Doppler effect becomes extreme, i.e.,... 

Because we are considering sedimentation of macromolecules as well as colloidal particles, in analyzing the kinematic wave fronts that will develop in the cell, we must also consider the broadening of these fronts that takes place due to diffusion. The geometry for analysis of a sector-shaped ultracentrifuge cell is shown in Fig. 5.5.2. The solvent-air interface (the meniscus) is located at r , and the bottom of the cell at... 

In heavy-particle collisions it is often not the resolving power of the electron spectrometer that limits the accuracy with which structures in ejected electron spectra can be measured, but the Doppler effect broaden-ings and shifts of the electron peaks severely influence the spectra and have to be taken into account in the analysis, or to be avoided by special means in the experimental setup. Since electron spectra due to heavy-particle collisions are treated in some detail in the following sections, we will briefly discuss the various kinematical effects. 

We will first describe spectroscopy on collimated atomic beams and on kinematically compressed ion beams. Two groups of nonlinear spectroscopic tecliniques will be discussed saturation techniques and two-photon absorption techniques. We will also deal with the optical analogy to the Ramsey fringe technique (Sect. 7.1.2). In a subsequent section (Sect. 9.8) laser cooling and atom- and ion-trap techniques will be discussed. Here, the particles are basically brought to rest, ehminating the Doppler as well as the transit broadening effects. 

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