Multiple‐Photon Infrared Laser Photophysics and Photochemistry. II

Баграташвили, В.Н.; Letokhov, V. S.; Макаров, А. А.; Ryabov, E. A.

doi:10.1155/lc.4.1

Cited by 59 publications

(87 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In the IRMPD process, a photon is absorbed when the laser frequency matches a vibrational mode of the gas-phase ion and its energy is subsequently distributed over all vibrational modes by intramolecular vibrational redistribution (IVR). The IVR process allows the energy of each photon to be dissipated before the ion absorbs another, which leads to the promotion of ion internal energy toward the dissociation threshold via multiple photon absorption [20]. It is important to note that studies have shown that infrared spectra obtained using IRMPD are comparable to those collected using linear absorption techniques [4,21].…”

Section: Infrared Multiple Photon Dissociation (Irmpd)mentioning

confidence: 99%

See 1 more Smart Citation

IRMPD spectroscopy of anionic group II metal nitrate cluster ions

Leavitt

Dain

Steill

et al. 2009

J. Am. Soc. Mass Spectrom.

View full text Add to dashboard Cite

Anionic group II metal nitrate clusters of the formula [M 2 (NO 3 ) 5 ] -, where M 2 ϭ Mg 2 , MgCa, Ca 2 , and Sr 2 , are investigated by infrared multiple photon dissociation (IRMPD) spectroscopy to obtain vibrational spectra in the mid-IR region. The IR spectra are dominated by the symmetric and the antisymmetric nitrate stretches, with the latter split into high and low-frequency components due to the distortion of nitrate anion symmetry by interactions with the cation. Density functional theory (DFT) is used to predict geometries and vibrational spectra for comparison to the experimental spectra. Calculations yield two stable isomers: the first one contains two terminal nitrate anions on each cation and a single bridging nitrate ("mono-bridging"), while the second structure features a single terminal nitrate on each cation with three bridging nitrate ligands ("tri-bridging"). The tri-bridging isomer is calculated to be lower in energy than the mono-bridging one for all species. Theoretical spectra of the tri-bridging structure provide a better qualitative match to the experimental infrared spectra of T he combination of ion-trapping mass spectrometers and free-electron lasers tunable through the mid-infrared region of the electromagnetic spectrum have provided invaluable access to the vibrational spectra of discrete, gas-phase metal complexes [1][2][3][4][5][6][7][8][9][10]. It is generally difficult to acquire a conventional linear absorption spectrum of species commonly investigated by mass spectrometry because of the low ion concentrations. However, use of an action spectroscopy approach allows photon absorption to be monitored by measuring fragmentation yields that result from wavelength-specific infrared multiple-photon dissociation (IRMPD) [11][12][13].Using the uranyl (UO 2 2ϩ ) and the europium (Eu 3ϩ ) cations, our group produced the first vibrational spectra of gas-phase metal nitrate anions of the formula [UO 2 (NO 3 ) 3 ] -and [Eu(NO 3 ) 4 ] - [14]. These experiments were carried out at the FOM Institute for Plasma Physics in Nieuwegein, The Netherlands, using the free electron laser for infrared experiments (FELIX). FELIX provides a tunable, high-intensity beam of photons across the mid-IR range to a high-resolution mass spectrometer. The IRMPD spectra of both the uranyl and europium nitrate anions are dominated by the antisymmetric nitrate stretch ( 3 ), which is split into low and high-frequency components corresponding to the O-N-O (O-atoms involved in bonding with the metal), and (non-coordinating) NϭO stretches respectively. Previous studies have shown that the splitting of the 3 (⌬ 3 ) is proportional to the interaction strength between the metal and the nitrate ligands [15,16]. In the uranyl and europium nitrate anions, ⌬ 3 was found to be 264 cm -1 and 273 cm -1 respectively [14].In a later study, IRMPD spectroscopy was used to record vibrational spectra of anionic group II metal nitrate complexes of the formula [M(NO 3 ) 3 ] -where M ϭ Mg 2ϩ , Ca 2ϩ , Sr 2ϩ , and Ba 2ϩ [17]. By observ...

show abstract

Section: Infrared Multiple Photon Dissociation (Irmpd)mentioning

confidence: 99%

“…The intensity of product and un-dissociated precursor ions is measured using the excite/detect sequence of the FT-ICR-MS after each IRMPD step [22]. The IRMPD yield is normalized to the total ion current, and linearly corrected for variations in laser power across the range scanned [4,19,20].…”

Section: Infrared Multiple Photon Dissociation (Irmpd)mentioning

confidence: 99%

IRMPD spectroscopy of anionic group II metal nitrate cluster ions

Leavitt

Dain

Steill

et al. 2009

J. Am. Soc. Mass Spectrom.

View full text Add to dashboard Cite

show abstract

“…Note that the ion has to absorb multiple photons (i.e., tens to hundreds) to reach the dissociation threshold. The mechanism of infrared multiple-photon dissociation (IR-MPD) has been described in detail previously [31,32]. In a separate experiment, [Trp ϩ K] ϩ was deuterated using a constant background pressure of ND 3 (8 ϫ 10 Ϫ7 mbar) for 6 s. The singly deuterated ion (at m/z 244) was again mass isolated and probed by IR spectroscopy, as described above.…”

Section: Experimental and Calculationsmentioning

confidence: 99%

Observation of zwitterion formation in the gas-phase H/D-exchange with CH₃OD: Solution-phase structures in the gas phase

Polfer

Dunbar

2007

J. Am. Soc. Mass Spectrom.

View full text Add to dashboard Cite

Infrared spectroscopy of gas-phase singly deuterated [Trp ϩ K] ϩ (formed by H/D exchange with CH 3 OD) shows that some (ϳ20%) kinetically stable zwitterionic (ZW) conformer is formed, based on the diagnostic antisymmetric CO stretch of the deprotonated carboxylate moiety, as (CO 2 Ϫ ), at 1680 cm Ϫ1 . A majority of the deuterated [Trp ϩ K] ϩ is found to be in the charge solvation (CS) conformation, with deuterium exchange occurring on both the acid and amino groups, which is consistent with H/D scrambling. Interestingly, H/D exchange with the more basic ND 3 reagent did not result in the stabilization of a kinetically stable zwitterion, although it is not clear yet what causes this observation. The result for CH 3 OD shows that H/D exchange can in fact alter the structure of the analyte and, hence, care needs to be taken when interpreting gas-phase H/D exchange studies. Moreover, this result shows the possibility of forming solution-phase structures that are thermodynamically disfavored in the gas phase, thus opening a new area of study. (HDX) is one of the most popular techniques for the structural elucidation of biomolecules in mass spectrometry and has been widely implemented for both solution [1][2][3][4] and gas phase studies [5][6][7][8][9][10][11][12][13][14][15][16][17][18]. In solution, the extent of HDX can be directly related to the solvent accessibility of amino acid residues in proteins. However, in the gas phase there are many structural parameters apart from the surface availability that affect the HDX rates, as illustrated in a recent HDX study on ion-mobilityselected charge states of bovine ubiquitin [17]. Systematic studies on small peptide systems showed that the difference in proton affinity of the biomolecules and deuterated donor reagent plays a crucial role in the HDX mechanism [7][8][9][10]19]. Beauchamp and coworkers [9] suggested that lower basicity reagents, such as D 2 O and CH 3 OD, proceed via a "relay" mechanism [20] for protonated peptides, while the higher basicity ND 3 reagent gives rise to an "onium" mechanism [21]. In the case of amino acids cationized by an alkali metal ion rather than a proton, polar deuterating ligands such as D 2 O can exchange via a similar relay mechanism involving charge solvation-zwitterion (CS-ZW) isomerization [18]. Modeling of observed HDX processes and quantum chemical calculations of the potential surfaces have made a strong circumstantial case that ZW structures are traversed in many cases during HDX with basic partners like D 2 O, CH 3 OD, and ND 3 [14,16,18]. Nevertheless, computations also generally indicate that the bare ZW is sufficiently disfavored energetically that its equilibrium presence in the M ϩ /amino acid would be negligible [22,23].Here, we show unambiguous spectroscopic evidence that bare ZW can in fact be kinetically trapped as a result of the HDX of [Trp ϩ K] ϩ with CH 3 OD. Infrared multiple-photon dissociation (IR-MPD) spectroscopy of metal-tagged amino acids and peptides has already been shown to be a powerful probe for CS ...

show abstract

“…28 It has been effectively argued that the transfer of energy by gas-phase collisions maybe too broad to define the subtle isomeric features within carbohydrate structures. For this reason, an alternative excitation strategy, infrared multiple-photon dissociation (IR-MPD), 29 was evaluated with a series of glucose disaccharide isomers. 30 In IR-MPD, the internal energy distribution, using mid-infrared wavelengths, is narrower than the thermal distributions acquired during CID, 31 and this method of energy transfer needs careful consideration.…”

mentioning

confidence: 99%

Carbohydrate Structural Isomers Analyzed by Sequential Mass Spectrometry

et al. 2007

View full text Add to dashboard Cite

Consistent with the goals of a comprehensive carbohydrate sequencing strategy, we extend earlier reports to include the characterization of structural (constitutional) isomers. Protocols were developed around ion trap instrumentation providing sequential mass spectrometry (MS n ) and supported with automation and related computational tools. These strategies have been built on the principle that for a single structure all product spectra upon sequential fragmentation are reproducible and each stage represents a rational spectrum of its precursor; i.e., all major fragments should be accounted for. Anomalous ions at any stage are clues indicating the presence of structural isomers. Gas-phase isolation and subsequent fragmentation of such ions provide an opportunity to specifically resolve selected structures for their detailed characterization. Importantly, some isomers were not detected following MS 2 and required multiple (MS n>2 ) stages for their characterization. Derivatization remains critical to position substructures in a glycan array since product ions carry fragmentation "scars" throughout the MS n tree. Equally as important are the pathway relationships between each stage and the greater yield of fragments with the smaller number of oscillators. Applications were directed to the structural isomers in ovalbumin and IgG, where, in the latter case, several previously unreported glycans were detected. Procedures were supported with bioinformatics tools for assimilating structure from the MS n data sets.A comprehensive carbohydrate sequence is particularly challenging when considering the constitutional and stereoisomers that are abundant in glycan arrays. Constitutional isomers, also referred to as structural isomers, are defined as an identical atomic composition arranged in a different structure. Stereoisomers are exemplified with those frequently encountered in the hexoses, mannose, galactose, and glucose, while the two G1 glycans found in IgG are representative of simple structural isomers. In this latter case, an identical monomer may be linked on either of two antennae providing a different topology. In another nomenclature clarification, the term isomer is often confused with isobar. which relates to a different composition of atoms occurring at a nominal (unit) mass resolution. 1 At the MS profile stage, isobars are not usually a significant problem in carbohydrate structural characterization, but structural isomers and stereoisomers are. During fragmentation, however, isobaric fragments may be formed, but identification will require higher mass resolving power and mass accuracy.

show abstract

Multiple‐Photon Infrared Laser Photophysics and Photochemistry. II

Cited by 59 publications

References 17 publications

IRMPD spectroscopy of anionic group II metal nitrate cluster ions

IRMPD spectroscopy of anionic group II metal nitrate cluster ions

Observation of zwitterion formation in the gas-phase H/D-exchange with CH₃OD: Solution-phase structures in the gas phase

Carbohydrate Structural Isomers Analyzed by Sequential Mass Spectrometry

Contact Info

Product

Resources

About

Multiple‐Photon Infrared Laser Photophysics and Photochemistry. II

Cited by 59 publications

References 17 publications

IRMPD spectroscopy of anionic group II metal nitrate cluster ions

IRMPD spectroscopy of anionic group II metal nitrate cluster ions

Observation of zwitterion formation in the gas-phase H/D-exchange with CH3OD: Solution-phase structures in the gas phase

Carbohydrate Structural Isomers Analyzed by Sequential Mass Spectrometry

Contact Info

Product

Resources

About

Observation of zwitterion formation in the gas-phase H/D-exchange with CH₃OD: Solution-phase structures in the gas phase