The construction of a small-size, magnetic sector, single focusing mass spectrometer (He-MS) for the continuous, on-site monitoring of He isotope ratios ((3)He/(4)He) is described. The instrument is capable of measuring (4)He/(20)Ne ratios dissolved in several different types of natural fluids of geochemical interest, such as groundwater and gas from hot springs, volcanoes and gas well fields. The ion optics of He-MS was designed using an ion trajectory simulation program "TRIO," which permits the simultaneous measurement of (3)He and (4)He with a double collector system under a mass resolution power (M/ΔM) of >700. The presently attained specifications of He-MS are; (1) a mass resolving power of ca. 430, sufficient to separate (3)He(+) from interfering ions, HD(+) and H3 (+), (2) ultra-high vacuum conditions down to 3×10(-8) Pa, and (3) a sufficiently high sensitivity to permit amounts of (3)He to be detected at levels as small as 10(-13) cm(3) STP (3×10(6) atoms). Long term stability for (3)He/(4)He analysis was examined by measuring the (3)He/(4)He standard gas (HESJ) and atmospheric He, resulting in ∼3% reproducibility and ≤5% experimental error for various amounts of atmospheric He from 0.3 to 2.3×10(-6) cm(3) STP introduced into the instrument. A dynamic range of measurable (3)He/(4)He ratios with He-MS is greater than 10(3) which was determined by measuring various types of natural fluid samples from continental gas (with a low (3)He/(4)He ratio down to 2×10(-8)) to volcanic gas (with a high (3)He/(4)He ratio up to 3×10(-5)). The accuracy and precision of (3)He/(4)He and (4)He/(20)Ne ratios were evaluated by comparing the values with those measured using well established noble gas mass spectrometers (modified VG5400/MS-III and -IV) in our laboratory, and were found to be in good agreement within analytical errors. Usefulness of the selective extraction of He from water/gas using a high permeability of He through a silica glass wall at high temperature (700°C) is demonstrated.

A new miniature double-focusing mass spectrograph has been designed and constructed. The ion optical system was designed based on Mattauch-Herzog geometry. The mass spectrograph employs a focal plane detector consisting of a microchannel plate, a phosphor layer, a fiber-optic plate and a charge-coupled device. For the evaluation of the ion optics of the instrument, the energy and angular focal planes were investigated both experimentally and by simulation. Double focusing was satisfactorily achieved along a straight line over a wide mass range, and the experimental and simulated results were mutually consistent. A second-order element of the transfer matrix was also measured experimentally and proved to be in good agreement with the simulated result.

A small multi-turn time-of-flight (TOF) mass spectrometer “MULTUM-S” was constructed, whose basic ion optical design was half that of the multi-turn TOF mass spectrometer “MULTUM II,” which consists of four toroidal electric sectors. Two additional electric sectors were introduced to inject and eject ions. The size of the analyzer was 20×20 cm. It was demonstrated that the mass resolution increased with the number of ion cycles in the multi-turn part, and a resolution of 4800 was obtained for electron ionization (EI), which generated xenon ions after 11 cycles.

A miniature mass spectrograph was newly designed and constructed as a prototype model for future lunar or planetary explorations. The ion optical system was newly designed based on Mattauch-Herzog geometry. The mass spectrograph employs a focal plane detector consisting of a microchannel plate (MCP), a phosphor layer, a fiber-optic plate (FOP) and a charge-coupled device (CCD). The 2D and 1D spectra of the residual gases, krypton and neon were observed in preliminary experiments. The mass resolution of 130 was achieved experimentally, and this was in good agreement with the simulation based on the transfer matrix method. The experimental value of the detectable m/z range was also consistent with the calculated version. Moreover, stable isotopes of Kr and Ne were observed without saturation of the detector. A dynamic range of 300 was achieved.

The reaction mechanisms of silver trimer cation, Ag3+, with 12-crown-4 (12C4) were studied experimentally and theoretically. Using a cylindrical ion trap time-of-flight mass spectrometer, gas-phase ion/molecule reactions of Ag3+ with 12C4 were observed. Metal-ligand complexes of [Ag(12C4)]+, [Ag3(12C4)]+ and [Ag3(12C4)2]+, and of [Ag(12C4)2]+ and [Ag3(12C4)3]+, were observed as the reaction intermediates and terminal products, respectively. The formations of the [Ag12C4]+ and [Ag(12C4)2]+ complexes indicated that the neutral dimer (Ag2) had been eliminated from the trimer cation. From the results of ab initio calculations at the HF/LanL2DZ level of theory and the experiments, it is suggested that three 12C4 molecules can attach to Ag3+ through consecutive reactions and that neutral Ag2 can be easily eliminated from [Ag3(12C4)]+.

For observing gas-phase ion/molecule reactions of metal cluster cations, a cylindrical ion trap time-of-flight mass spectrometer was newly constructed. This apparatus consists of an external sputtering ion source, ion deceleration lens system, cylindrical ion trap and time-of-flight mass analyzer with four toroidal electric sectors. Using this apparatus, ion/molecule reactions of silver cluster cation, Ag5+, with crown ether, 12-crown-4 (12C4), were observed. The cluster-ligand complexes, [Ag5(12C4)n]+ (n=1–3) and fragmentations of the cluster induced by adducts of crown ether molecules were also observed.

The circuit shape of the ion path, or the multi-turn, provides a solution for achieving unrestricted mass resolution from time-of-flight mass analyzers. The potential of a multi-turn type mass spectrometer, the MULTUM II, with a 1.308 m circuit controlled by four toroidal electric sector fields in biological applications was examined. With matrix-assisted laser desorption/ionization, the ion flight of 18 cycles gave a mass resolution of 10 000 for MH+ of protophorphyrin IX This resolution was correlated with the flight length, and a resolution of 61 000 was achieved for MH+ of angiotensin I after 75 cycles or a 98.75 in total flight. The results demonstrate that the multi-turn mass spectrometer allows not only high resolution but also very high separation of the ions of molecular species from organic compounds. Copyright (C) 2004 John Wiley Sons, Ltd.

A mass spectrograph using a position sensitive detector was designed and constructed. It has an image contractor lens system and a zoom lens system. The position sensitive detector consists of a micro channel plate (MCP) and a charge-coupled device (CCD). The performance of this new instrument was tested with methylstearate as a sample.

The fragmentation of doubly and triply charged mercury cluster ions were investigated. The cluster ions were produced by Xe ions bombardment on a mercury-silver amalgam. The size where evaporation and fission occur with equal probability is called appearance size. The appearance sizes of doubly and triply charged mercury cluster ions were determined to be Na2+=20, and Na3+=46, respectively. The fission channels were investigated and their probability was estimated by calculation of Q-values. The van der Waals bonding of small mercury clusters caused the symmetric fission of doubly charged cluster ions. The fission channels of triply charged cluster ions were asymmetric since the metallic character came into prominence for both precursor and large one of fission fragments.

The lifetime distribution of silver and mercury-silver binary cluster ions from a sputtering ion source was investigated. The cluster ions were produced by 10 keV Xe ion bombardment on a mercury-silver amalgam for mercury-silver binary clusters, and a silver plate for silver clusters. The fragmentation rates were obtained from experimental data at several positions of the mass spectrometer. The lifetime distribution was calculated using fragmentation rates. The distribution was found to be rather power functional than exponential, because of the wide distribution of lifetimes for cluster ions. The cluster ion, Hg12Ag+, which might have an icosahedron structure turned out to be more stable than neighboring clusters.

A handy electrospray ion source that made use of commercially available spray device for cosmetic foundation was designed and manufactured. The performance of the handy ion-source for electrospray ionization mass spectrometry (ESI-MS) was evaluated with a triple-stage quadrupole mass spectrometer. The ion intensities and distribution of multiply charged ions obtained in positive ion mass spectra of cytochrome c and polyethyleneglycol (PEG) showed that the handy ESI source exhibited the same performance as the existing ESI source.

In the studies on dissociation patterns of clusters using a single focusing mass spectrometer, product ions decomposed between a main slit and an entrance of a magnet appear in mass spectra at mass Map= Mpro2/Mpre, whereMpro denotes the mass of product ions and Mpre; mass of precursor ions. In the case of decomposition from cluster size nto n-m(n>m), the product ions appear at size of (n-m)2/n. When n is much larger than m, (n-m)2/n is very close to (n-2m), and it is difficult to resolve the dissociated n and undissociat ed (n-2m) cluster ions. In order to study on decomposition patterns of clusters, we attached the TOF function to the sector type mass spectrometer and detected product ions. We attached the chopper in front of the main slit to get the pulsed beam and use silver clusters as the sample.

The size distribution of iron-sulfur binary cluster ions, FenSm+ (n=1-36, m=1-23), was investigated using secondary ion mass spectrometry (SIMS). The dissociation patterns, n=2-26, m=1-17, were also investigated by varying the acceleration voltage of secondary ions step by step. Iron-sulfur binary cluster ions were produced by 10 keV Xe ion bombardment on a pyrite (FeS2) sheet and were mass-analyzed by a sector type mass spectrometer. Judging from the size distribution observed in mass spectra, the composition ratio n/m of the cluster ions gradually tended to increase as the cluster size became larger. The dissociation patterns of small size tended to yield the FenSn+ (n=2, 4, 6) and FenSn-1+ (n=7, 8, 9) which might be more stable structure. As the cluster size became larger, the dissociation mainly occurred by emitting Fe or S2. Dissociation patterns of FenSm+ suddenly changed at FenSM+ which had maximum peak intensity in the series of FenSm+ for the fixed n. In case of m≤M, Fe emission occurred and S2 emission for m>M

Generally, an ion source is supplied with high voltage to accelerate ions. However, the high voltage on the ion source makes some difficulties in applying pulse voltage or introducing samples, etc. We developed a new ion source to solve these problems. This new ion source consists of a grounded ionization region, an acceleration region and a cylinder. While the electric potential of the cylinder is varied, the electric field in the cylinder does not change and the kinetic energy of the ions in the cylinder is independent of the potential of the cylinder. After the ions formed in the ion source at the ground potential go into the cylinder at the accelerating potential, the electric potential of the cylinder is varied from the accelerating potential to the ground potential. By this method, ions keep accelerated velocity after the cylinder. To confirm this idea, we constructed a time-of-flight (TOF) mass spectrometer having an ion source and an analyzer, both of which are at the ground potential.

Mass spectra of doubly charged tellurium clusters were investigated by a secondary ion mass spectrometry. Cluster ions were produced by the Xe ions bombardment on the tellurium sheet and were mass-analyzed using a grand-scale sector type mass spectrometer. Te22+, Te32+, and Te52+ were observed.

Mass spectra of doubly charged mercury clusters (m/z=30-1065) were investigated by secondary ion mass spectrometry. Positively charged ions were generated from an amalgam of mercury and silver by bombardment with a xenon ion beam and mass analysis by a grand-scale sector type mass spectrometer. Hg n 2+, n=1-10 and Hg n +, n =1- 5 were observed. Some doubly charged mercury clusters, (Hg n 2+) survived at least for 0.1 ms.

We have made a cooled sputter ion source for producing clusters of volatile samples. A sample holder was cooled by coolant sent by a tube pump from outside of vacuum chamber. The temperature at sample holder reached to -10°C. Stable ion current of mercury-secium clusters, (Hg)nCs+ type, were observed for long time.