English
J. Mass Spectrom. Soc. Jpn., 50(1), 1-6, 2002
An ion trajectory simulation code based on a stochastic sampling method was developed for pressurized events in Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. The ion-neutral interaction was modeled by discrete collisions and was characterized by appropriate probability density functions. The use of randomization allows a more realistic representation of ion behaviors than a conventional approach, such as a viscous drag model. Besides, the proposed simulation can depict a time-varying internal energy, which may provide a useful measure for collisionally activated decomposition processes. The simulation code has been applied to various experimental situations of pressurized events; sustained off-resonance irradiation, quadrupolar excitation axialization and rf-only-mode trapping. The simulation results revealed the dynamics and the energetics of a trapped ion undergoing these pressurized events.
English
J. Mass Spectrom. Soc. Jpn., 50(1), 7-10, 2002
Hydrogen-atom elimination channels in 121.6-nm photodissociation of formic acid were investigated by a Doppler-selected TOF mass spectrometry (DS-TOF-MS). This mass spectroscopic method enables us to map out three dimensional velocity distributions of photodissociated products through multiphoton ionization for the H atoms, and therefore we can determine anisotropic parameter b. The H+HCOO* channel is found to be a main branching among many H elimination channels. A new three-body channel of H+CO+OH is observed. We estimate that the H+HCOO* channel is more favor than the H+CO+OH channel by a factor of 
5. Other H-elimination channels such as H+HCOO, 2H+CO2, H+HOCO, and H+CO+OH(A) are found to be small. These results show that the DS-TOF-MS method is useful to determine branching ratios and internal energy distributions of photodissociated products in excited states as well as ground states in addition to anisotropic parameter determination.
English
J. Mass Spectrom. Soc. Jpn., 50(1), 11-14, 2002
In order to study cluster beams, it is essential to measure their mass and velocity distributions as the fundamental characteristics. We demonstrate an experimental method to simultaneously measure both the mass spectrum and the beam velocities by the orthogonal acceleration time-of-flight mass spectrometer. The method is based on the ion-interruption effect of the electrode wire-mesh in the accelerator. The neutral clusters are photoionized in a small area in the accelerator, accelerated perpendicularly to the cluster beam axis, mass-analyzed and detected. Depending on the mass and the beam velocity, specific ions are interrupted by the wires arranged with a equal spacing and can not reach the detector. This ion-interruption effect modulates the transmittance of the ions, yielding the apparent oscillations in the mass spectra. Unfolding these modulated mass spectra, we have successfully measured both the mass spectrum and the beam velocities as a function of the mass simultaneously.
English
J. Mass Spectrom. Soc. Jpn., 50(1), 15-17, 2002
The mass spectra of Co(II) acetylacetonate and Co(III) acetylacetonate were measured by MALDI-TOF-MS. Complex peaks, such as the adduct peaks and cluster peaks, were observed in their mass spectra. The two compounds had different mass spectra. The compounds could be identified by their mass spectra. TLC-MALDI-TOFMS was applied to a mixture of these compounds. The separated spots on the TLC plate gave similar mass spectra to that of the conventional MALDI-TOFMS, when a mixture of solvents with acetylacetone was used as the developing and eluting solvents.
English
J. Mass Spectrom. Soc. Jpn., 50(1), 18-20, 2002
The formation of Paraquat complexes with deoxyguanosine, guanosine, and 9-ethylguanine were detected by electrospray ionization-mass spectrometry.
English
J. Mass Spectrom. Soc. Jpn., 50(1), 21-23, 2002
Capillary isoelectric focusing (CIEF) separation combined with mass spectrometry for protein analysis has been demonstrated by using a sonic spray ionization (SSI) interface, which has a buffer reservoir between the ion source and the separation capillary. Since the buffer reservoir was used as an outlet reservoir for CIEF, on-line and one-step CIEF/MS was possible. In SSI, since a sample solution is sprayed at any solution-flow rate from a sample-introduction capillary with a high-speed gas flow, high-polymer ampholytes for CIEF can be used without clogging up the spray nozzle of the interface. Also, additives such as ampholytes significantly decrease ion intensity of analyte molecules; however, the SSI interface whose reservoir is filled with an acetic acid solution minimizes the decrease in ion intensity of the analyte. We combined CIEF with an ion trap mass spectrometer and were able to detect 160 fmol of myoglobin and cytochrome-c.
Japanese, English Abstract
J. Mass Spectrom. Soc. Jpn., 50(1), 24-32, 2002
A double charge transfer (DCT) spectrometer has been developed to study doubly charged molecular ions (molecular dications). For N22+, CO2+, and C2H22+, vibrationally resolved DCT spectra were observed for the first time. The advantages of DCT spectroscopy are shown by comparing with other spectroscopic methods that enable to resolve the vibrational states of molecular dications. Details of the spectrometer are also described.
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