Infrared-induced dissociation

E. Thermal Infrared-Induced Dissociation of Cluster Ions... 

DGE a AC AMS APCI API AP-MALDI APPI ASAP BIRD c CAD CE CF CF-FAB Cl CID cw CZE Da DAPCI DART DC DE DESI DIOS DTIMS EC ECD El ELDI EM ESI ETD eV f FAB FAIMS FD FI FT FTICR two-dimensional gel electrophoresis atto, 10 18 alternating current accelerator mass spectrometry atmospheric pressure chemical ionization atmospheric pressure ionization atmospheric pressure matrix-assisted laser desorption/ionization atmospheric pressure photoionization atmospheric-pressure solids analysis probe blackbody infrared radiative dissociation centi, 10-2 collision-activated dissociation capillary electrophoresis continuous flow continuous flow fast atom bombardment chemical ionization collision-induced dissociation continuous wave capillary zone electrophoresis dalton desorption atmospheric pressure chemical ionization direct analysis in real time direct current delayed extraction desorption electrospray ionization desorption/ionization on silicon drift tube ion mobility spectrometry electrochromatography electron capture dissociation electron ionization electrospray-assisted laser desorption/ionization electron multiplier electrospray ionization electron transfer dissociation electron volt femto, 1CT15 fast atom bombardment field asymmetric waveform ion mobility spectrometry field desorption field ionization Fourier transform Fourier transform ion cyclotron resonance... 

Output from both gated continuous wave and pulsed carbon dioxide lasers has been used to desorb ions from surfaces and then to photodissociate them in a Fourier transform ion cyclotron resonance mass spectrometer. Pulsed C02 laser irradiation was most successful in laser desorption experiments, while a gated continuous wave laser was used for a majority of the successful infrared multiphoton dissociation studies. Fragmentation of ions with m/z values in the range of 400-1500 daltons was induced by infrared multiphoton dissociation. Such photodissociation was successfully coupled with laser desorption for several different classes of compounds. Either two sequential pulses from a pulsed carbon dioxide laser (one for desorption and one for dissociation), or one desorption pulse followed by gated continuous wave irradiation to bring about dissociation was used. 

This is the highest molecular weight compound for which infrared multiphoton dissociation has been observed in our laboratories to date. A similar pathway was indicated by the collision-induced dissociation spectrum of this ion. Limited CID experiments were performed on some of the other laser-desorbed ions discussed here and in general the CID and PD pathways were the same. 

Other fragmentation techniques have been introduced [108]. Some of these, e.g., sustained off-resonance irradiation (SORl) and infrared multiphoton dissociation (IRMPD), provide similar fragmentation as in CID, i.e., preferential backbone cleavages at the peptide amide bond (b- and y-ions). Others like electron-capture dissociation (ECD) [109-110] induce different fragmentation reactions, i.e., the formation of c- and z -ions due to cleavage of N-C bonds. 

F. Chateauneuf, T.T. Nguyen-Dang, N. OueUet, O. Atabek, Dynamical quenching of field-induced dissociation ofHf in intense infrared lasers, J. Chem. Phys. 108 (1998) 3974. 

Fragmentation of peptide and protein ions in FT-ICR mass spectrometry may be induced by sustained off-resonance irradiation collision-induced dissociation (SORI-CID) [28], infrared multiphoton dissociation (IRMPD) [29,30], blackbody infrared radiative dissociation (BIRD) [31,32], surface-induced dissociation (SID) [33,34], and electron capture dissociation (ECD) [35,36]. These techniques are true MS/MS techniques in which the precursor ion is isolated prior to fragmentation. Additional techniques in which ions are not isolated but fragmented before they... 

A distinction is made between fragmentation inside the ion source and those occurring in other locations. Although the processes taking place in MS/MS are still fragmentations, specific names are used to indicate the type of processes, e.g., collision-induced dissociation (Section 3.3.2.1), infrared multiphoton dissociation (Section 3.3.2.2), electron transfer dissociation and electron capture dissociation (Section 3.3.2.3), as well as the more specialized photodissociation and surface-induced dissociation (Section 3.3.2.4). 

Yoo HJ, Liu H, Hakansson K. Infrared multiphoton dissociation and electron-induced dissociation as alternative MS/MS strategies for metabolite identification. Anal Chem 2007 79 7858-7866. 

In an FT-ICR instrument, fragmentation may be achieved by colliding ions with neutrals (CID) but various other strategies are available, such as collision with surfaces (surface-induced dissociation) or bombardment with ultraviolet or infrared radiation from a laser (ultraviolet photodissociation and multiphoton infrared photodissociation). Dissociation may also be achieved by the absorption of black-body radiation produced by a heated vacuum chamber walls (blackbody infrared dissociation). An advantage of these radiation-induced fragmentation methods is that gas pulses are no longer required. Sustained off-resonance irradiation is the preferred, radiation-based method for FT-ICR MS because it is the simplest to implement and tune. Very low energy and multiple excitation collisional activation techniques are also available. 

Activation of the vibrational energy of ions can also be induced by the absorption of IR radiations. A popular type of IR radiation source is far-IR laser. In fact, many molecules have a broad IR absorption band. The most widely used IR source is a continuous wave (c.w.) CO2 laser, with the wavelength of 10.6 pm. This wavelength corresponds to an energy of 0.3 eV per laser photon. Because decomposition of a chemical bond requires >1 eV, laser excitation has to extended over hundreds of milliseconds to allow ions to absorb multiple IR photons. This method is known as infrared multiphoton dissociation (IRMPD). Another type of similar technique is black-body infrared radiative dissociation... 

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