Massive cluster ions of CsI (mass-to-charge ratio > 25,000) have been produced, mass analyzed, and detected with a conventional double-focusing mass spectrometer. Variations in the ion intensity distributions depend on the relative lifetime of the ions. These results are of fundamental interest, but they also impact the practical limits of mass spectrometry.
BarlakT. M.CampanaJ. E.ColtonR. J.DeCorpoJ. J., and WyattJ. R., J. Phys. Chem.85, 3840 (1981).
3.
ColtonR. J.CampanaJ. E.BarlakT. M.DeCorpoJ. J., and WyattJ. R., Rev. Sci. Instrum.51, 1685 (1980). The original instrument was a spark source, Mattauch-Herzog geometry, mass spectrometer designed to operate at 25 kV acceleration voltage.
4.
CampanaJ. E.BarlakT. M.ColtonR. J.DeCorpoJ. J.WyattJ. R., and DunlapB. I., Phys. Rev. Lett.47, 1046 (1981).
5.
BarlakT. M.WyattJ. R.ColtonR. J.DeCorpoJ. J., and CampanaJ. E., J. Amer. Chem. Soc.104, 1212 (1982).
6.
BarberM.BordoliR. S.ElliottG. J.SedgwickR. D., and TylerA. N., Anal. Chem.54, 645A (1982). The technique of FABMS has historically denoted the atom bombardment of a sample dissolved in a liquid matrix. The experiments described in this report did not use a liquid matrix for simplicity; nevertheless, the technique will be referred to as FABMS.
7.
The term “cubic-like” is used to account for the simple cubic salts (NaI) and the body-centered cubic salts (CsI) whose rhombohedral structure can be viewed as a skewed cube.
8.
MorganR. P.BeynonJ. H.BatemanR. H., and GreenB. N., Int. J. Mass Spectrom. Ion Phys.28, 171 (1978). The mass spectrometer was a ZAB-HF, manufactured by VG Analytical Ltd., Wythenshawe, Manchester M23 9LE, U.K. The resolving power used (100) was the minimum required to resolve the positive ion CsI cluster n = 99 from n = 98 in the single-focusing mode of operation. The resolving power was ∼300 in the double-focusing mode.
9.
Pioneering investigations of ultra-high mass species have been conducted by a few researchers using non-standard mass spectrometers: Unresolved mass spectra of polystyrene (200,000 amu) using an electrospray technique with an ion-drift spectrometer, K. Nakamac, V. Kumar, and M. Dole, Proceedings of the 29th Annual Conference on Mass Spectrometry and Allied Topics, May 24–29 (1981), Minneapolis, MN, pp. 517–18; unresolved water clusters up to 60,000 amu have been observed using a special quadrupole mass filter and electronics system, BeuhlerR. J. and FriedmanL., Nucl. Instrum. Methods, 170, 309 (1980); mass-resolved polystyrene oligomer distributions of 10,000 amu using field desorption and a toroidal mass spectrometer, MatsuoT.MatsudaH., and KatakuseI., Anal. Chem.51, 1329 (1979); plasma desorption mass spectrometry of oligonucleotides yielding a dimeric cluster ion of m/z 12,637 ± 10 by time-of-flight mass spectrometry, McNealC. J. and McFarlaneR. D., J. Amer. Chem. Soc.103, 1607 (1981).
10.
BarlakT. M.CampanaJ. E.WyattJ. R., and ColtonR. J., Int. J. Mass Spectrom. Ion Phys.46, 523 (1983).
11.
EnsW.BeavisR., and StandingK. G., Phys. Rev. Lett.50, 27 (1983). An ion in a time-of-flight mass spectrometer needs to remain stable long enough to be fully accelerated so that its subsequent decomposition products appear at the original mass number.
12.
CampanaJ. E. and DunlapB. I., Int. J. Mass Spectrom. Ion Proc., in press.
