Internal energy molecular origin

Quite apart from thermolysis occurring before fragmentation, the temperature of the ion source may have a marked effect on the appearance of a mass spectrum. Comparison of mass spectra obtained with hot and cooled ion-sources and of spectra obtained by photon impact or field ionization show by the increased amount of fragmentation that a molecular ion possesses a greater excess of internal energy when formed in a hot, electron-impact source. Possible origins of this excess internal energy are collision with or radiation from surfaces. Some effects of hot and cold ion sources are discussed. 

The mechanical spectra and temperature dependencies derived from DMA provide, as such, no immediate insight to their molecular origin. Qualitatively the various viscoelastic phenomena are linked to the energy-elastic deformation of bonds and the viscous effects due to large-amplitude movement of the molecular segments. The latter are based on internal rotation causing conformational motion to achieve the equilibrium entropy-elastic response. 

MALDI-conditions [47] and also predicted by molecular modeling [40, 50], However, these model calculations also predicted that large clusters would have insufficient internal energy for a complete dissociation with evaporation of the neutrals. This result may also originate from insufficient simulation times and/or to too-hmited sizes of the simulation box [58], and does not necessarily reflect the situation for smaller to medium-sized clusters. While the initially charged matrix - analyte cluster ions never appear in the MALDI spectra with the typical solutes used, such as trifluoroacetic acid (TFA) or ammonium salts, they have been detected for extremely strong acids [60] their conjugate anions are extremely weak bases and thus stabiUze the formed ion pairs with protonated analyte sites. 

The dynamic properties of the Mossbauer nucleus which can be monitored as a result of their effect on the Mossbauer spectrum can arise from the lattice dynamics of the solid in which the nucleus is situated. It can also result from the motion of a localised part of the system, such as a molecular motion, or from motion of the whole system within its environment. As the effect on the spectrum depends only on the actual motion of the nucleus and not on its origin it is not possible to distinguish directly between the possible sources of any such motion. Since the motion is often related to the internal energy of the system under investigation it is frequently studied as a function of the various parameters which determine the behaviour of the system, and particularly the temperature. 

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