Collisional energy

A chromophore that emits a photon is called a fluorophore. Many chromophores do not necessarily fluoresce. In this case, energy absorbed is dissipated within the environment as thermal energy, collisional energy as the result of permanent collisions with the solvent molecules, and also energy transfer to other molecules. For example, heme does absorb light, but it does not fluoresce. The absence of fluorescence is the result of total energy transfer from the porphyrin ring to iron. 

Hsu, F.-F., and Turk, 1 1999. Structural Characterization of triacylglycerols as lithiated adducts by electrospray ionization mass spectrometry using low-energy collisionally activated dissociation on a triple stage quadrupole instrument. J. Am. Soc. Mass Spectrom., 10, 587-599. 

Fig. 5. High energy collisionally induced dissociation mass spectrum for molecular ion MH+ m/z 1149 in fraction 9 (see Fig. la) corresponding to tryptic peptide P(133-144). Significant ions indicating the sequence are labeled.

The high-energy collisional activation (CA) spectra of the C6H60 + ions (wt/z 94) or C7HgO + ions (wt/z 108) were recorded and the resulting spectra depicted in Figure 35 were found identical to the corresponding spectra of ionized phenol or anisole, respectively. 

Such behaviour clearly contrasts with the case of 4-iodoaniIine, where protonation in a chemical ionization source occurred not only on the ring but also on the nitrogen atom . Nitrogen protonation was indicated by ion-molecule reactions with dimethyl disulphide consecutive to collisional dehalogenation (FT-ICR experiments) or by an increase in the intensity of the peak at mjz 76 following high-energy collisional activation . 

LC Taylor, RL Johnson, L St John-Williams, T Johnson, SY Chang. The use of low-energy collisionally activated dissociation negative-ion tandem mass spectrometry for the characterization of dog and human urinary metabolites of the drug BW 1370U87. Rapid Commun Mass Spectrom 8 265, 1994. 

Tusa, Sulkes, and Rice have also obtained data for the zero-energy collisional relaxation of the levels l , P, 6a, and 12 of Rj aniline. In each case only a very few of the energetically accessible levels are coupled to the initial level by the coUision, so the selectivity of the vibrational relaxation process is retained in the zero-energy mechanism. 

Fast Atom Bombardment-Fourier Transform-Mass Spectrometry (FAB-FT-MS) and low-energy collisional activation experiments proved that the oligomers of j3-ketolactone generally have a macrocyclic ring structure rather than a catenane ring. ... 

Huang Y, Liu S, Miao S, Jeanville PM. Using multiple mass defect filters and higher energy collisional dissociation on an LTQ Orbitrap XL for fast, sensitive, and accurate metabolite ID, 2008, available www.thermo.com/appnotes. 

There is a class of experiments in prospect or progress with cold molecules that could answer questions reaching far beyond the scope of traditional molecular science these experiments test some of the fundamental symmetries in physics, such as the time-reversal symmetry (T), parity (P), and the Pauli principle. These symmetries are a window into the world of the fundamental forces in nature and thus molecular, table-top experiments that test them are complementary to the high-energy collisional experiments. 

FTMS/MS data are acquired at a resolving power of 60,000 ( m/z 400). Both collision-induced dissociation (CID) and higher energy collisional dissociation (HCD) are performed for structural identification of analyte molecules. For the latter, the collision cell placed in elongation to the curved linear ion trap is used see 6). Precursor ion isolation is achieved in the linear ion trap for both kinds of fragmentation techniques. As for the molecular (MS mode) ions, also the fragment (MS/MS mode) ions are analyzed in the Orbitrap detector in these experiments. 

Hsu FF, Turk J. Electrospray ionization with low-energy collisionally activated dissociation tandem mass spectrometry of glycerophospholipids mechanisms of fragmentation and structural characterization. J Chromatogr B. 2009 877 2673-95. 

Hsu F-F, Turk J, Stewart ME, Downing DT. Structural studies on ceramides as lithiated adducts by low energy collisional-activated dissociation tandem mass spectrometry with electrospray ionization. J Am Soc Mass Spectrom. 2002 13 680-95. 

Hsu, E.-E. and Turk, J. (2005) Electrospray ionization with low-energy collisionally activated dissociation tandem mass spectrometry of complex lipids Structural characterization and mechaiusm of fragmentation. In Modern Methods for Lipid Analysis by Liquid Chromatography/Mass Spectrometry and Related Techiuques (Byrdwell, W.C., ed.). pp. 61-178, AOCS Press, Champaign, IL. 

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