Development of a photoinduced fragmentation ion trap for infrared multiple photon dissociation spectroscopy (original) (raw)
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Review of Scientific Instruments, 2005
A Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer has been installed at a free electron laser (FEL) facility to obtain infrared absorption spectra of gas phase ions by infrared multiple photon dissociation (IRMPD). The FEL provides continuously tunable infrared radiation over a broad range of the infrared spectrum, and the FT-ICR mass spectrometer, utilizing a 4.7 Tesla superconducting magnet, permits facile formation, isolation, trapping, and high-mass resolution detection of a wide range of ion classes. A description of the instrumentation and experimental parameters for these experiments is presented along with preliminary IRMPD spectra of the singly-charged chromium-bound dimer of diethyl ether ͑Cr͑C 4 H 10 O͒ 2 + ͒ and the fluorene molecular ion ͑C 13 H 10 + ͒. Also presented is a brief comparison of the fluorene cation spectrum obtained by the FT-ICR-FEL with an earlier spectrum recorded using a quadrupole ion trap (QIT).
Gas-phase infrared multiple photon dissociation spectroscopy of mass-selected molecular ions
International Journal of Mass Spectrometry, 2006
In this review, we present an overview of our recent work on the infrared spectroscopy of mass-selected gas-phase molecular ions. The ions are stored and isolated in a quadrupole ion trap where they are investigated with infrared multiple photon dissociation spectroscopy using a free electron laser (FEL). The wide and continuous tunability of FELIX, the FEL for Infrared eXperiments at the FOM institute for Plasma Physics in The Netherlands, allows us to explore the interesting mid-infrared range between 500 and 2000 cm−1, sometimes referred to as the fingerprint region. The experiments have focused on polycyclic aromatic hydrocarbons because of their hypothesized occurrence in the interstellar medium, both in neutral and cationic forms. Furthermore, several related species of fundamental chemical interest have been investigated, such as molecular fragment ions and protonated species. The spectra are compared to theoretical spectra calculated at the density functional theory level. The effects of multiple photon excitation and dissociation dynamics on the appearance of the spectrum are extensively discussed. A mathematical model to account for the effects of anharmonicity is described. It explains for instance, qualitatively, how the observed spectral response can vary (slightly) with the fragment channel, which allows one to “direct” dissociation reactions in a non-coherent fashion by the choice of the infrared excitation wavelength.
Infrared multiple photon dissociation in the quadrupole ion trap via a multipass optical arrangement
Journal of the American Society for Mass Spectrometry, 1994
The design of a novel multipass optical arrangement for use with infrared multiple photon dissociation (IRMPD) in the quadrupole ion trap is presented. This design circumvents previous problems of limited IR laser power, small IR absorption cross sections for many molecules, and the limited ion statistics of trapping and detection of ions for IRMPD in the quadrupole ion trap. In contrast to previous designs that utilized the quadrupole ion store, the quadrupole ion trap was operated in the mass selective instability mode with concurrent resonance ejection. The instrumental design consisted of a modified ring electrode with three spherical concave mirrors mounted on the inner surface of the ring. This modified design allowed for eight laser passes across the radial plane of the ring electrode. IRMPD of protonated bis(2-methoxyethyllether (diglyme) was used to characterize the performance of the multipass ring electrode. Two consecutive reactions for the IRMPD of protonated diglyme were observed with a lower energy channel predominant at less than 0.6 J (irradiation times from 1 to 30 ms) and a second channel predominant at energies greater than 0.6 J (irradiation times > 30 ms). Other studies presented include a discussion of the dissociation kinetics of protonated diglyme, the use of a pulsed valve for increased trapping efficiency of parent ion populations, and the effects of laser wavelength and of ion residence time in the radial plane of the ring electrode on photodissociation efficiency. (1 Am Sot Mass Spectrom 1994, 5, 886-893) 0 ver the past 15 years photodissociation has become an integral tool in the study of gasphase ion chemistry [l, 21. The combination of mass spectrometry (employing both ion trap and ion cyclotron resonance instruments) and photodissociation has been used successfully to investigate the chemical kinetics, reactivity, and spectroscopy of various ionic species [3-91. The long storage times and instrumental configuration of trapping instruments are ideally suited for photodissociation experiments. Some capabilities of trapping instruments include the measurement of photon-induced ion decay as a function of laser irradiance time, the use of the multiphoton absorption process to study fragmentation, and the use of the photodissociation spectrum as a fingerprint for determination of isomeric ion structures [ 101.
Analytical Chemistry, 1996
(SWIFT) to effect dissociation and ion ejection in a quadrupole ion trap mass spectrometer. The application of IRMPD to the structural characterization of biochemical ions generated by chemical ionization and electrospray ionization and the feasibility of utilizing infrared photons for the activation of laser-desorbed metal ion-crown ether complexes was examined. The effect of helium pressure on the dissociation efficiency and relative dissociation rate constants for systems with well-known thermochemistry was evaluated. The helium pressure is not detrimental to the IRMPD experiment when nominal pressures lower than 2 × 10 -5 Torr are used. At pressures close to nominally 8 × 10 -5 Torr of helium, collisonal deactivation dominates. Results show conventional CAD is a more selective dissociation technique; however, the amount of fragment ion information generated depends highly on the q Z value. IRMPD, on the other hand, is independent of the value of q Z such that low rf storage values can be utilized during the irradiation period. Thus, under these conditions, informative lower mass fragment ions are trapped and detected. A larger number of structurally informative fragments is generated upon irradiation with infrared photons relative to the CAD method because of the further excitation of primary fragment ions upon photoabsorption. SWIFT wave forms are successfully utilized to determine the extent of excitation of primary fragment ions as well as prove/disprove dissociation pathways of a variety of ions such as macrolide antibiotics and hydrogen-bonded complexes.
Canadian Journal of Chemistry, 1983
A versatile technique employing pulsed quadrupole ion storage mass spectrometry and a low power CW CO2 laser for the study of slow infrared multiphoton dissociation of gaseous ions under collision-free conditions is described. Multiphoton dissociation of gaseous ions derived from isopropanol. 2-d1-isopropanol, isopropan-d-ol and perdeutcroisopropanol, with irradiation for up to 110 ms with intensities of ~20 W cm−2, was effected. Irradiation of proton (or D+) bound alcohol dimers showed that three dissociative reaction channels are utilized in multiphoton dissociation: the photodissociation yield for the dissociative reaction channel of lowest activation energy increases and becomes dominant with collisional and radiative relaxation of the ions. Of the three ionic photoproducts of multiphoton dissociation of proton bound alcohol dimers, only the protonated ether is found to be photodissociative under the prevailing conditions. The photochemical stability of the ion formed by loss of...
Analytical Chemistry, 2006
Variation in the wavelength of irradiation in infrared multiple-photon dissociation (IR-MPD) of lithium-tagged glucose-containing disaccharide ions (1-2-, 1-3-, 1-4-, and 1-6-linked isomers of both anomeric configurations) resulted in marked differences in their mass spectral fragmentation patterns. Two-dimensional plots of the fragment yield versus infrared wavelength for each mass spectral product ion were unique for each isomer and can be considered a spectral fingerprint. Individual product ions or diagnostic ratios of key product ions can be optimized at specific IR wavelengths. The technique permits both linkage position and anomeric configuration to be assigned. The ratio of the fragments derived by cleavage at the glycosidic bond (m/z 169/187) is much enhanced for-anomers compared to r-anomers. Differences in the diagnostic product ions 169 and 187 were largest in the range of 9.0-9.4 µm, where the maximum dissociation yield was observed. Conversely, at 10.6 µm, the wavelength of nontunable CO 2 lasers that accompany commercial Fourier transform ion cyclotron resonance mass spectrometers, the dissociation yield was poor and anomeric differentiation was not possible. In contrast to previous studies by collision-induced dissociation, the trends in dissociation behavior between anomers using IR-MPD are significant and allow simple diagnostic rules to be established. By depositing energy into these isobaric ions via narrow-band IR excitation, the resulting internal energy can be finely controlled, thereby obtaining high reproducibility in dissociation patterns. Given the multidimensionality of variable-wavelength IR-MPD of lithiated disaccharides, it is expected that this approach can overcome some of the current limitations in isomer differentiation.
Analytical Chemistry, 1992
Photodiesodatlon (PD) and wrlact+hducd dbrodatlon (SID) are compared for structural analyrk of several nonvdatlle compounds analyzed by laser dosorption Fowler transform mass spectrometry (LD/FTMS). SID and PD of a porphyrin and two metalloporphyrin8 were Investlgated udng a varkty of experimental conditions. Optimum structural Information le obtained from PD when parent ions are hradlated for relatively long tlmes (10-30 8 ) wkrg 575-nm radiation and short times (0.5-1 8 ) udng 308-or 388-nm radiation. Shorter Irradiation the8 In the vklMe r e g h resulted In less Wlcknt productlon of structurally rlgnmcant product ions, whlk longer times In the ultraviolet region produced mare nonrp.ciflc fragmeni Ions, apparently at the exp.nu, of more structurally significant I r m n t ions. SID conv.nkn effkiencks for the porphyrins are estimated for collkkn enorgkr from 25 to 360 eV, with maxl" coqverrkn dfkloncy found urlng 82-and 1 1 5 -e V c o l t d o n e~( o r t h e t w o p o r p h y r l n r ,~. R~ from a concurrent study on the combined use of PD and SID for MS/MS/MS are discussed In the context of these results.
Mass and Isotope-Selective Infrared Spectroscopy
Handbook of High-resolution Spectroscopy, 2011
Recent advances in laser spectroscopic techniques make it possible to obtain mass-and isotope-selective infrared spectra of gas-phase species at high resolution and reduced hot-band spectral congestion. In these techniques, infrared excitation is coupled with ultraviolet multiphoton ionization and detection of the resulting ions in a mass spectrometer, which allows the separation of contributions of different isotopomers and, more generally, species of different mass in a mixture. In combination with jet cooling techniques, spectra are obtained for very cold molecules. These spectra can then be analyzed to extract information on dynamical processes such as intramolecular vibrational redistribution or tunneling and rearrangement processes, and on how intramolecular dynamics is influenced by vibrational excitation and isotope effects. In this review, we introduce isotope-selective infrared spectroscopic techniques and present some selected applications on isotope effects and intramolecular dynamics of vibrationally excited chloroform, aniline, and benzene obtained by isotope-selective infrared spectroscopy.