r. kelly sang life is what you make it.
r. kelly sang life is what you make it.
who sings life is what you make it?
r. kelly
Na
Na
in order to study the inelastic scattering of the helium atom beam due only to single-phonon contributions, an energy analysis needs to be made of the scattered atoms. the most popular way to do this is through the use of time-of-flight (tof) analysis. the tof analysis requires the beam to be pulsed through the mechanical chopper, producing collimated beam 'packets' that have a 'time-of-flight' (tof) to travel from the chopper to the detector. the beams that scatter inelastically will lose some energy in their encounter with the surface and therefore have a different velocity after scattering than they were incident with. the creation or annihilation of surface phonons can be measured, therefore, by the shifts in the energy of the scattered beam. by changing the scattering angles or incident beam energy, it is possible to sample inelastic scattering at different values of energy and momentum transfer, mapping out the dispersion relations for the surface modes. analyzing the dispersion curves reveals sought-after information about the surface structure and bonding. a tof analysis plot would show intensity peaks as a function of time. the main peak (with the highest intensity) is that for the unscattered helium beam 'packet'. a peak to the left is that for the annihilation of a phonon. if a phonon creation process occurred, it would appear as a peak to the right:
helium atom scattering