Hoffman D.M., Singh B., Thomas J.H. (Eds). Handbook of Vacuum Science and Technology

Подождите немного. Документ загружается.

320 Chapter 3.2: Mass Analysis and Partial Pressure Measurement

Ions obtain their initial velocity, v, by acceleration through an electric field,

E, thus:

Combining the two equations results the "magnetic mass spectrometer equation":

M B^r^

(7)

Q IE

Since the source and the collector are usually at fixed positions, the two options

"scan"

—

i.e.,

change the radius of the ion beam according to MIQ is to either

vary the magnetic field strength, B (using an electromagnet) or to use a fixed

magnet and vary the strength of the accelerating electric field E (voltage scan-

ning).

In either case the relationship between MIQ and the scanning variable is

nonlinear, resulting in a nonlinear mass axis. (The space between the peaks is

smaller (the spectrum is "compressed") at the high end as compared with the

lower MIQ end.)

To prevent ions with widely different angles of velocity (and energy) to enter

the spectrometer, an entrance slit is used that reduces the yield of the ion source,

defining the beam size. For proper resolution, an exit slit is used that allows only

those ions to enter the detector that are focused. (Magnetic sector field instru-

ments of this type provide single focusing—ions of equal MIQ and energy but

divergent direction of velocity at the entrance are focused on the exit slit.) For the

greatest sensitivity, the width of the entrance slit {S\) should be as great as pos-

sible.

The width of the exit slit (^2) has to be even larger by A^ to allow for

a wider beam caused by the aberration due to variation in initial directions

(5*2

Sx + 5). In this case the resolving power will be [156]

— = — (8)

AM 252

Directional focusing can be achieved with various beam deflection angles. In

the Dempster-type instrument the ion beam is deflected in a 180-degree sector

field, thus the ion beam is parallel through the entrance and the exit slits, but mov-

ing in opposite directions. The ion source and the detector are within the mag-

netic field in this configuration.

There may be a need to remove the source and the detector from the magnetic

field for easier access and to eliminate interferences with multipliers. This is pos-

sible using 30-, 60-, or 90-degree sector fields. To ensure focusing, the entrance

and exit slits must be on the line perpendicular to the symmetry axis of the mag-

net, the line being placed at the point where the field boundary lines intersect

(Figure 6). This arrangement will provide for single (directional) focusing effect.

3.2.4 Ion Separation and Analyzers

321

Rg.6.

Transverse

field

AcceIerat

VoItage

oooo ooooooo

o o o o_o_o o o o o o

' O O O 0^—6"^ O O*^*-©^ O O

JO^'^OOO OOOO o'^vp O O Oy

\o^'^ooooo ooooooo"

2,^

oooooo ooooooo

oooo ooooo

oooooo ooooooo o

p.^

ooo ooooo

oooo oooooo

o o oooo

\ /

Ent ranee slit

Schematic of a magnetic single-focu.sing analyzer (60 degrees).

Exit si it

Alignment of the magnet is typically more critical in this arrangement and there-

fore recalibration may be necessary after removing it (e.g., for bakeout).

These single-focusing spectrometers separate ions according to MIQ from a

monoenergetic ion beam. Since there is an unavoidable spread in energy, only an

additional electrostatic deflection can provide directional and energy focusing.

Such a double-focusing instrument for partial pressure analysis has been described

byNier[157].

In all cases mechanical parts (entrance and exits slits) must be changed to af-

fect sensitivity and resolution. Compared to quadrupoles (change in electronic

setting), this may be a limitation if frequent changes are needed, but may be an

advantage in stability and repeatability depending on the application. Resolving

power M/AM is constant throughout the mass range, and typical scanning speeds

are of the order of a few amu/s.

The coupling of a magnetic sector analyzer (90-degree) to a Nier-type electron

source has been studied by Werner

[110].

At low emission currents (< 50/>tA)

and low pressures (less than 10"^ torr or about 10""^ Pa) the source magnetic

field, the initial thermal energy and negative as well as positive space charge ef-

fects could be neglected. At higher emission currents and low pressures, negative

space charge; at high pressures, positive space charge may influence the poten-

tials,

leading to variation in ion energy. Mass discrimination during voltage scan-

ning can be explained by a decrease in the size of the ion formation region and by

an increase in the angular divergence due to the reduction in accelerating voltage.

At low accelerating voltage (corresponding to higher mass numbers), the ion tra-

jectories have shown a larger divergence and concentration on the edges of the

322 Chapter 3.2: Mass Analysis and Partial Pressure Measurement

exit slit. As opposed to this, at higher accelerating voltage (2 kV) the ions are con-

centrated along the axis (higher transmission at lower mass numbers).

3.2.4.3 Time-of-Flight Analyzers

Ions are generated by a short pulse of transverse electron beam in the source,

which is followed by another voltage pulse (extraction) to provide ions with a cer-

tain kinetic energy. The residence time of the ions in this accelerating region,

will depend on their MIQ ratio (T{M/Q)). Based on Equation (1),

-~Tr{M/Q) = Er{M/Q) (9)

2 "'

From energy considerations—or integrating Equation (9) along the path of the

ions in the constant field E—the velocity of the ions will be proportional to the

square root of their mass:

2EQ

(The kinetic energy of an ion equals the energy gained from the electric field.)

If these ions are let drift along a field-free tube (drift tube of a length /), the time

required to reach the detector will depend on their MIQ ratio, enabling mass

analysis:

, M

J (11)

Whereas sensitivity will be proportional to the duration of the ionizing pulses,

resolving power will be proportional to the ratio of ion flight time to the duration

of the ion extracting pulse (typically ^ts). Therefore the length of the drift tube is

critical in determining resolution (drift tube length of

meter or more is typical).

Although this is the simplest analyzer structure of all PPAs, rather complex driv-

ing circuitry is required to provide the pulses and detection of

ions.

Reaction stud-

ies and study of fast-changing processes use the extremely short response time of

this instrument.

Some instruments employ techniques to improve resolving power, which is

limited by—beside the length of the tube—the energy spread of ions formed at

different regions in the source (space focusing, time lag focusing techniques)

[158].

Time-of-flight instruments can be coupled relatively easily to electron impact

ionizers. Ions generated by electron bombardment are held in the potential well

3.2.5 Detection of Ions 323

formed by the electron beam traveling at right angle to the axis of the instrument.

A pulse applied to the extraction grid perpendicular to the axis will deflect the

beam, and the ions are extracted through this grid. Several other grids can be ap-

plied to reduce field penetration of the drift tube (0-3 kV) in the source

[159].

For XHV measurements (<

"'^ torr, ~

10 ~ ^^

Pa) segregation of gas-phase ions

from electron stimulated desorption related ions is a major challenge. A

time-of-

flight quadrupole has been constructed for such low pressure measurements

[160].

3.2.5

DETECTION OF IONS

The ions leaving the analyzer have been separated from each other qualitatively

(according to MIQ), but their abundances need to be measured for quantitative

analysis or just simple identification purposes. Therefore the ion signal is con-

verted into an electric signal by either simply converting the ion current into an

electron current in a metal electrode (Faraday collector) or in a way that also pro-

vides for amplification (multipliers).

3.2.5.1 Faraday Collectors

Ions striking a metal surface are neutralized by electron transfer—the related cur-

rent when the metal is held at constant potential can be measured through a large

ohmic resistor. A current to voltage converter then can produce a signal propor-

tional to the ion current, however, double-charged ions will produce a signal twice

as high as the corresponding ion stream (ion/s) compared to single-charged ions.

In its simplest form the Faraday collector is only a metal plate following the

exit of the analyzer. A major drawback of this simple device is that the incident

ions may eject secondary electrons when striking into the metal surface, causing

a higher measured current than the corresponding ion current. Gold plating is a

way to minimize secondary electron emission.

Secondary electron effects can also be minimized by using a closed structure

except for the aperture for ions to enter (Faraday cup). Secondary electrons then

hit a surface inside the cup and be recaptured, and so their effect is eliminated.

Another solution is to use an additional grid before the Faraday cup to act as an

electron suppressor (held at a potential well below that of the Faraday cup).

A limitation of

the

Faraday collector is its speed of measurement. This is related

to the capacitance of input cables and the necessity to use high-input resistors. At

10~^^

A, a time constant is typically about

s. Measurement at such low current

324 Chapter 3.2: Mass Analysis and Partial Pressure Measurement

levels are limited by noise, the main sources of which are the cables and connec-

tors and ultimately the thermal noise produced by the resistor

[161].

X2.5.2 Discrete Dynode Multipliers

To overcome limitations such as speed of measurement, sensitivity, and dynamic

range, electron multipliers are used. These devices make use of the secondary elec-

tron emission —

phenomenon being suppressed in Faraday collectors. In a dis-

crete dynode multiplier the ions are accelerated by voltages of the order of kilo-

volts,

and directed to the front end (first dynode) of the multiplier. Secondary

electrons in a number greater than the number of impinging ions are emitted from

this surface and accelerated to the second dynode. On impact, even more sec-

ondary electrons are emitted. Repeating this process through several stages (14-

16 are typical) amplification by a factor of 10^ can be achieved. The electron cur-

rent from the last dynode is measured by a Faraday collector. The overall gain of

given multiplier depends on the voltage applied in a stronger-than-linear fashion.

The principal secondary emission material used is most often beryllium-copper

(beryllium-oxide layer as the secondary emitting surface), but silver-magnesium

and aluminum have also been used

[162].

The requirements for the multipliers are (beside high secondary emitting ratio),

the stability of the gain over time and possibly following exposure to samples. As

a first approximation, it is assumed that the gain varies as Af~^^ as a result of

the ion-electron conversion efficacy being proportional to the velocity of the ion

(which at constant energy varies as M~^^). Unfortunately the gain also depends

on the type of the ion {MIQ)

[161],

and on the state of the surfaces that emit sec-

ondary electrons. Exposure to samples or contamination may cause severe deterio-

ration of gain, making frequent checks necessary. Gain measurement can be ac-

complished by comparing the signal obtained using the multiplier with the signal

collected when the

first

dynode is used as

Faraday collector. Rejuvenation of mul-

tipliers after a decrease in their gain have been reported to be successful (such as

baking in 1 atm of

at 300°C) [162,163].

If further increase in sensitivity is needed, the multiplier can be operated as an

"ion counter," extending the detection limit to a single ion.

3.2.5.3 Channel Electron Multipliers

Instead of a complex structure of many dynodes, a compact single piece of spe-

cial (high-lead) glass tube can be used that exhibits high secondary emission

characteristics. High voltage (kV) applied to contacts on both ends provides for

replenishing the charge lost and also accelerates the secondary electrons. In prin-

3.2.5 Detection of Ions 325

ciple there is no difference between this device and the discrete dynode multi-

plier, but the small size and lower cost make it appealing. One ion will produce

typically a pulse of about 10 ns width (at half height).

To eliminate ion feedback (ions created by secondary electrons from residual

gases,

hitting the walls and creating a further burst of secondary electrons) the

tube is curved limiting the distance an ion can travel and the amount of energy

they can acquire. Some channel electron multipliers (CEMs) [164] have been de-

signed especially for pulse-counting

mode.

These devices allow the use of discrim-

inators to distinguish between signal and noise simply based on pulse amplitude.

The lifetime depends on exposure time to high input levels (ion bombardment of

front surfaces), and also the residual gas environment, which may cause degrada-

tion of

the

secondary emissive surface

[165],

but in general CEMs are less suscep-

tible to gain change resulting from exposure to air than discrete dynode multipliers.

A method for measuring CEM gain based on the ratio of DC current and noise

current eliminates the need to measure gain by switching cables and particularly

suitable for CEMs

[166].

Besides multiplier voltage, the gain depends on the ion

mass,

incident energy, and chemical nature of

the

ion (typically decreases with in-

creasing mass number) requiring the use of correction factors

[167].

3.2.5.4 MicroChannel Plate Multipliers

An extension and integration of the CEM with the fiber optic technology resulted

in the appearance of microchannel plate multipliers (MCPs). MicroChannel plates

are thin lead glass plates with millions of 10

/mm

diameter holes acting as parallel

short CEMs. The walls of the holes are treated to create a high-resistance coating

with higher than 1 coefficient of secondary emission. High voltage is applied on

the top and the bottom surfaces of the plate, coated with a conductive layer. The

channels are set at an angle to ensure that electrons traveling normally to the plate

will strike the wall. To eliminate ion feedback two of these plates are placed on

each other ("Chevron configuration")

[168].

MCPs are especially well suited to

quadrupole analyzers, providing a large area for detection, but magnetic sector

spectrometers have also applied it successfully

[169].

As with other multipliers,

strong ion signals can cause saturation due to space charge or field distortion in

the output. Contamination of the surfaces can cause field emission, which in a se-

vere case can lead to a permanently saturated state. MCPs are extremely fragile,

and if they must be removed from the vacuum environment they should be stored

in desiccated containers to avoid breakage due to moisture takeup. Short exposure

to atmosphere (few hours) will generally not lead to performance losses; how-

ever, exposure to hydrocarbon vapors or operation in vacuum but at elevated tem-

peratures (above 50°C) may cause permanent damage.

326 Chapter 3.2: Mass Analysis and Partial Pressure Measurement

REFERENCES

R. Schubert, Anal. Cliem., 44 (1972) 2084-2087.

J. Hardy, Advances in Mass Spec.,6(1974)

1061

-107.

K. Anderson and K. Mauersberger, Rev. Sci. Instrum., 52 (1981) 1025-1028.

K. Mauersberger and R. Finstad, Rev. Sci. Instrum., 50 (1979) 1612-1617.

Leybold Inficon Inc., American Environmental Laboratory, (1995) Nov.-Dec, 34-35.

6. F. R. Lauritsen, Int. J. Mass Spec. Ion Proc, 95 (1990) 259-268.

S. Bohatka, I. Futo, and I. Gal, Vacuum, 44 (1993)

669-671.

8. S. Bohatka,

Vacuum,

46 (1995) 767-768.

9. S. Bohatka and I. Berecz, Vakuum Technik., 35 (1986) 79-88.

10.

G. Langer, Vacuum, 34 (1984) 757-784.

11.

S. Hiroki et al., J.

Vac.

Sci. Teclmol., A12 (1994)

2711

-2715.

12.

C. M. Hohenberg, Rev. Sci. Instrum., 51 (1980) 1075-1082.

13.

I. R Wright, I. A. Boyd, and S. R. Franchi, J. Phys. E. Sci. Instrum., 21 (1988) 865-875.

14.

F. E. Jones and F E. Cartan, Report # ICP-I085, 1976 (Available from the Nat'l Technical In-

formation Service, 5285 Port Royal Road, Springfield VA 22161.)

15.

J. Dattner and J. Fischler, fim. J. Appl. Phys., 14 (1963) 728-729.

16.

R. E. Ellefson and D. Cain, J.

Vac.

ScL TechnoL, A5 (1987) 134-139.

17.

D. J. Santeler, /

Vac.

Sci. Teclmol., A5 (1987) 129-133.

18.

E. Danes, R. Dobrozemsky, and G. Schwarzinger, Vacuum, 43 (1992) 537-539.

19.

L. Lieszkovsky, and J. Borossay, J.

Vac.

Sci. Teclmol., A5 (1987) 2819-2822.

20.

J. Koprio, and G. Rettinghaus, Advances in Mass Spec, 10 (1985) 891-892.

21.

R. T. Parkinson and L. Toft, Analyst, 90 (1965) 220-227.

22.

J. Roboz, Anal. Chem., 39 (1967) 175-178.

23.

E. E. Hughes and W. Dorko, Anal.Chem., 40 (1968) 750-755.

24.

I. Morisako, I. Kato, and Y. Ino, Int. J. Mass Spec. Ion Phys., 48 (1983) 19-22.

25.

K. Siefering, H. Berger, and W. Whitlock, J.

Vac.

Sci. Teclmol., All (1993) 1593-1597.

26.

G. M. Solomon, J.

Vac.

Sci. Teclmol., A2 (1984) 1157-1161.

27.

H. Selhofer and R.Wagner, Proc. 7th Intern. Vac. Congr., Vienna 1977, (1977) 211-214.

28.

I. Berecz and S. Bohatka, Proc. 8th Intern. Vac. Congr., Cannes 1980, (1980)

251

-254.

29.

A. Holme, J. D. Buckingham, and K. T. Fowler, Dynamic Mass Spectrometiy, 5 (1978)

129-136.

30.

B. Goodwin, A. E. Holme, and J. H. Leek, Proc. 7th

Intern.

Vac.

Congr. Vienna 1977, {[911)

177-180.

31.

A. E. Holme, M.Parris, and S. Purdy, J.

Vac.

Sci. Teclmol., A6 (1988) 1156-1157.

32.

I. Niishi, S. Sugai, and K. Kimura, Proc. 6th Intern. Vac. Congr. Kyoto 1974, (1974) 163-166.

33.

A. Smith and M. J. Pcttifor, Vacuum, 32 (1982)

175-181.

34.

J. M. Welter, Proc. 6th

Intern.

Vac.

Congr.

Kyoto 1974, (1974) 175-178.

35.

O. G. Koch and R. Reinhard,

Fres'Z.

Anal. Chem., 231 (1967) 420-429.

36.

W. G. Perkins, J.

Vac.

Sci. Teclmol., 10 (1973) 543-556.

37.

G. Thieme, Vacuum, 13 (1963) 137-143.

38.

R. S. Barton and R. P Govier, J.

Vac.

Sci. Teclmol, 2 (1965) 113-122.

39.

M. Mosharrafa and H. J. Oskam, Physica., 32 (1966) 1759-1765.

40.

J. J. Sullivan and R. G. Buser, J.

Vac.

Sci. TechnoL, 6 (1969) 103-108.

41.

H. F Dylla, W R. Blanchard, and R. B. Krawchuk, J.

Vac.

Sci. TechnoL, A2 (1984) 1188-1192.

42.

W. Poschenrieder. J.

Vac.

ScL TechnoL, A5 (1987) 2265-2272.

43.

C. G. Pearce, Advances in Mass Spec.,8(1980)

1771

-1777.

44.

H. F. Dylla, Proc. 9th

Intern.

Vac.

Congr.

Madrid 1983, (1983) 578-588.

45.

H. F. Dylla, J.

Vac.

ScL TechnoL, Al (1983) 1297-1301.

References 327

46.

W. R. Blanchard, H. J. McCarthy, and H. F. Dylla, J.

Vac.

ScL TechnoL, A4 (1986) 1715-1719.

47.

R. Dobrozemsky and G. Schwarzinger, J.

Vac.

Sci. TechnoL, AlO (1992) 2661-2664.

48.

J. H. Scrivens,

Vacuum,

32 (1982) 169-174.

49.

R L. Swart and H. Aharoni, J.

Vac.

Sci.

TechnoL,

A3 (1985) 1935-1945.

50.

J. Visser, J.

Vac.

Sci. TechnoL, 10 (1973)

464-471.

51.

N. Muller, G. Rettinghaus, and G. Strasser, J.

Vac.

ScL

TechnoL,

A8 (1990) 2822-2825.

52.

M. E. Buckley,

Vacuum,

44 (1993) 665-668.

53.

B. Raby, J.

Vac.

ScL TechnoL, 15 (1978) 205-208.

54.

A. J. G. Schellingerhout, T. M. Janocko, and M. A. Klapwijk, Rev. ScL Instrum., 60 (1989)

1177-1183.

55.

J. A. Koprio, G. Peter, and H. Fischer, Vacuum, 38 (1988) 783-786.

56.

M. Benyezzar, D. King, and R L. Jones,

Vacuum,

43 (1992) 21-24.

57.

E. Hasler and G. Rettinghaus,

Vacuum,

38 (1988) 1-5.

58.

C. Lu, M. J. Lightner, and C. A. Gogol, J.

Vac.

ScL TechnoL, 14 (1977) 103-107.

59.

C. A. Gogol and S. H. Reagan, J.

Vac.

ScL

TechnoL,

Al (1983) 252-256.

60.

R. Kubiak, J.

Vac.

ScL

TechnoL,

Al (1991) 2423-2427.

61.

P. Looney and S. Tison (eds.). Water: Its Measurement and Control in Vacuum (Gaithersburg

1994).

62.

R. K. Lowry, NBS IR 84-2852, Proc. Moist. Meas. Workshop (National Bureau of Standards,

Gaithersburg, 1984), p. 59.

63.

L. J. Rigby, Int. J. Mass Spec. Ion Proc, 60 (1984)

251

-264.

64.

K. L. Perkins, NBS SP 400-69, Proc. Moist. Meas. Workshop (National Bureau of Standards,

Gaithersburg, 1981), p. 58.

65.

K. Lin and J. D. Burden, J.

Vac.

ScL TechnoL, 15 (1978) 373-376.

66.

T. J. Rossiter, F. GoUob et al. NBS IR 84-2852, Proc. Moist. Meas. Workshop (National Bureau

of Standards, Gaithersburg, 1984), 8-23.

67.

W. M. Hickam, NBS SP 400-69, Proc. Moist. Meas. Workshop (National Bureau of Standards,

Gaithersburg, 1984), p. 153.

68.

J. E. Fenstermacher, J.

Vac.

ScL TechnoL, 8 (1971) 380-384.

69.

S. Baptist and R Levy,

Vacuum,

43 (1992) 213-214.

70.

J. E. Fenstermacher, J.

Vac.

ScL TechnoL, A5 (1987) 142-143.

71.

A. Pebler and W M. Hickam, AnaL Chem., 45 (1973) 315-319.

72.

S. K. Gupta, Analyst, 109 (1984) 793-794.

73.

R. Schubert and J. A. Augis, J.

Vac.

ScL

TechnoL,

Al (1983)

248-251.

74.

D. G. Mahoney, J.

Vac.

ScL

TechnoL,

A12 (1994) 1740-1743.

75.

C. M. Ward and L. E. Bergquist, J. NucL Mat., 85 (1979) 117-120.

76.

J. A. Koprio, H. Gang, and H. Eppler, Int. J. Mass Spec. Ion Phys., 48 (1983) 23-26.

77.

L. J. Rigby, Dynamic Mass Spectrometiy, 3 (1972) 237-242.

78.

O. G.Koch,

Fres'Z.

AnaL Chem., 284 (1977) 13-18.

79.

Y. Rosenthal, G. Adam, and G. Kohn, J.

Vac.

ScL TechnoL, X5 (1987) 389-390.

80.

M. C. Paul, Vacuum, 15 (1965) 239-247.

81.

S. Watanabe, M. Aono, and S. Kato, J.

Vac.

ScL TechnoL, A14 (1996) 3261-3266.

82.

W. Nesseldreher,

Vacuum,

26 (1976)

281

-286.

83.

J. R. J. Bennett and R. J. Elsey,

Vacuum,

44 (1993)

647-651.

84.

W. L. Fite and R Irwing, J.Vac. ScL TechnoL, 11 (1974) 351-356.

85.

R. J. Reid, Vacuum, 28 (1978) 499-505.

86.

C. Wursching, Vacuum, 43 (1992)

137-141.

87.

B. Podor, L Bertoti, and G. Mink,

Vacuum,

33 (1983) 71-72.

88.

R. D. Pilkington and D. Price, Dynamic Mass Spectrometry, 6 (1981) 284-290.

89.

H. Eppler and H. Selhofer, Thermochimica Acta, 20 (1977) 45-52.

90.

R. D. Collins, R Fiveash, and L. Holland, Vacuum, 19 (1969) 113-116.

328 Chapter 3.2: Mass Analysis and Partial Pressure Measurement

91.

K. Hoefler, A. Hoeglund, and L. G. Rosengren,

Int.

J. Mass

Spec.

Ion Pliys.,46 (1983) 127-130.

92.

B. R. F. Kendall, V. S. Rohrer, and V. J. Bojan, J.

Vac.

Sci. TechnoL, A4 (1986)

598-601.

93.

Y. Wang and Z. Yang,/ Phys. E: Sci. Instrum., 20 (1987) 1483-1486.

94.

J. Basford, M. Boeckmann, R. EUefson, A. Filippelli, D. Holkeboer, L. Lieszkovszky, and

C. Stupak, J.

Vac.

Sci.

Techno!.,

All (1993) A22-A40.

95.

Lieszkovszky, A. R. Filippelli, and C. R. Tilford, J.

Vac.

Sci. Techno!., A8 (1990) 3838-

3854.

96.

J. H. Batey, Vacuum, 44 (1993) 639-642.

97.

G. Bunyard, Vacuum, 44 (1993) 633-638.

98.

I. E. Sodal and D. A. Hanna, J.

Vac.

Sci. Tedmo!., A15 (1997)

176-181.

99.

R E. Gear, Vacuum, 26 (1976) 3-10.

100.

B. Podor, Vacuum, 33 (1983) 67-68.

101.

J. H. Batey, V^/cm/w, 43 (1991) 15-19.

102.

A. Nicr,

/?6'v.

Sci. lustrum., 18 (1947)

398-411.

103.

L. Dietz, Rev. Sci. lustrum., 30 (1959)

235-241.

104.

J. F. J. Todd and H. S. McKown, Int. J. Mass Spec. Ion Pliys., 42 (1982) 183-190.

105.

S. Dworetsky, R. Novick, and W.Smith, Rev. Sci. lustrum., 39 (1968) 1721-1723.

106.

W. M. Brubaker, D. Biirnham, and G. Perkins, /

Vac.

Sci. Tedmo!., 8 (1971) 273-2741.

107.

R S. Naidu and K. O. Wcstphal, Brit. J. Appi P!iys., 17 (1966)

645-651.

108.

W. Fock, //;/. J. Mass Spec. Ion Pliys., 3 (1969)

285-291.

109.

H. W. Werner, J. Pliys. E: Sci. lustrum.,7(1974)

115-121.

110.

J. L. Segovia, Vacuum, 47 (1996) 333-340.

111.

F. Watanabe and H. Ishimaru, J.

Vac.

Sci. Tedmo!., A3 (1985) 2192-2195.

112.

H. Miyake and M. Michijima, Proc. 6th Intern. Vac. Congr. Kyoto, 1974 (1974) 17

-174.

113.

B. Hu and J. Qiu, J.

Vac.

Sci. Tedmo!., A5 (1987) 2657-2660.

114.

C. He-neng, A. J. Genuit, W. Boerboom. and J. Los, Int. J. Mass Spec. Ion P!iys., 46 (1983)

277-280.

115.

K. Kokubun, S. Ichimura, and H. Shimizu, Vacuum, 44 (1993) 657-659.

116.

F. Daublin,

Val<uum-Tec!mili,

20 (1971) 72-78.

117.

W. Aberth and C. Spindt, Int. J. Mass Spec. Ion Pliys., 25 (1977) 183-198.

118.

N. Ogiwara and M. Shiho, Vacuum, 44 (1993) 661-663.

119.

W. Brubaker, Proc. 5th

lustrum.

Measiu:

Conf.

Stoddwim

^961

(1961) 305-315.

120.

R H. Dawson, Int. J. Mass Spec. Ion Pliys., 14 (1974) 317-337.

121.

J. E. Campana, Int. J. Mass Spec. Ion

P!iys.,

33 (1980) 101-117.

122.

W. M. Brubaker, in Metliods of Experimenta! Pliysics, Vol. 14, edited by G. L. Weissler and

R. W. Carlson (Academic Press, New York, 1979), pp. 81-100.

123.

W M. Brubaker and J.Tuul, Rev. Sci. lustrum., 35 (1964) 1007-1010.

124.

S. Hiroki, T. Abe, and Y Murakami, Rev. Sci. lustrum., 62 (1991) 2121-2124.

125.

S. Hiroki, T. Abe, and Y. Murakami, Rev. Sci. lustrum., 63 (1992) 3874-3876.

126.

G. Reich, Proc.

7th

Intern.

Vac.

Congr

Vienna

I977i\911) 197.

127.

L. Frees, D. Holkeboer, and J. Farden, 30th

Annu.

Conf.

Mass Spec. &

AHied Topics Hono!u!u

7952(1982)656-656.

128.

L E. Dayton,

C. Shoemaker, and R. F. Mozley, Rev. Sci. lustrum., 25 (1954) 485-495.

129.

D. R. Denison, J.

Vac.

Sci. Tedmo!., 8 (1971) 266-269.

130.

J. Y. Tu, y. Pliys. E: Sci. lustrum., 22 (1989) 368

-372.

131.

W. M. Brubaker and W. S. Chambcrlin, NASA Re. NASW 7295 (1970) 98-103.

132.

J. F. Hennequin and R. L. Inglebert, Int. J. Mass Spec. Ion Pliys. 26 (1978)

131

-135.

133.

R. L. Inglebert and J. F. Hennequin, Advances in Mass Spec, 8 (1980) 1764-1770.

134.

R H. Dawson, Mass Spectrometry Reviews, 5 (1986) 1-37.

135.

R H. Dawson, J.

Vac.

Sci.

Techno!.,

A4 (1986) 1709-1714.

References

329

136.

A. E. Holme, W. J. Thatcher, and J. H. Leek, J. Phys. E: Sci Instnim., 5 (1972) 429-433.

137.

P. H. Dawson, Adv. Electron. & Electron Phys., 53 (1980) 153-208.

138.

P. H. Dawson, Int. J. Mass Spec. Ion Phys., 6 (1971) 33-44.

139.

W. M. Brubaker, Advances in Mass Spectrometry, 4 (1967) 293-299.

140.

C. Trajber, M. Simon, and S. Bohatka,

Vacuum,

44 (1993) 653-656.

141.

U. Brinkmann, Int. J. Mass Spec. Ion Phys. ,9(1972)

161

- 166.

142.

A. E. Holme, Int. J. Mass Spec.Ion Phys., 22 (1976)

-5.

143.

A. E. Holme, S. Sayyid, and J. H. Leek, Int. J. Mass Spec. Ion Phys., 26 (1978) 191-204.

144.

P H. Dawson, M. Meunier, and W. Tam, Advances m Mass Spec, 8 (1979) 1629-1637.

145.

J. A. Richards, R. M. Huey, and J. Hiller, Int. J. Mass Spec. Ion Phys., 15 (1974) 417-428.

146.

T. Hayashi and N. Sakudo, Rev. Sci. Instrum., 39 (1968) 958-968.

147.

C. G. Pearce and D. Halsall, Int. J. Mass Spec. Ion Phys., 27 (1978)

31-41.

148.

S. Hiroki at. al..

Vacuum,

44 (1993) 71-74.

149.

H. Matsuda, and T. Matsuo, Int. J. Mass Spec. Ion Phys., 24 (1977) 107-118.

150.

U. von Zahn, Rev. Sci. Instrum., 34 (1963)

-4.

151.

PH. Dawson, Int. J. Mass Spec. Ion Phys., 12 (1973) 53-85.

152.

L Szabo, Int. J. Mass Spec. Ion Proc, 73 (1986) 197-235.

153.

R. J. Ferran and S. Boumsellek, J.

Vac.

Sci. Technoi, A14 (1996) 1258-1265.

154.

D. Goeringer, R. Crutcher, and S. McLuckey, Anal. Chem., 67 (1995) 4164-4169.

155.

W. C. McDonald, B. Abraham, and A. Robbat Jr., Environ. Sci. Technoi, 28 (1994) 336A-

343A.

156.

G. F. Weston,

Vacuum,

30 (1980) 49-67.

157.

A. Nier, Rev. Sci.Instrum., 31 (1960) 1127.

158.

W. C. Wiley and L H. McLauren, Rev. Sci. Instrum., 26 (1955) 1150-1157.

159.

D. B. Wilson, Vacuum, 19 (1969) 323-325.

160.

N. Ogiwara, Y. Miyo, and Y. Ueda, Vacuum, 47 (1996) 575-578.

161.

R. D.Collins, Vacuum, 19(1969)

105-111.

162.

R. Young, Rev. Sci. Instrum., 37 (1966) 1414-1417.

163.

G. Salser, Rev. Sci. Instrum., 37 (1966) 674-675.

164.

E. Kurz, American Laboratory, 3 (1979) 67-82.

165.

S. Kaszczyszyn and A. Grzeszczak, Vacuum, 45 (1994) 323-324.

166.

W. J. Fies, Int. J. Mass Spec. Ion Proc., 82 (1988)

111

-129.

167.

N. R. Reagan, L. C. Frees, and J. W Gray, J.

Vac.

Sci. Technoi, A5 (1987) 2389-2392.

168.

G. F Vanderschmidt, J.

Vac.

Sci. Technoi, A9 (1991) 2001-2006.

169.

D. Murphy and K. Mauersberger, Rev. Sci Instrum., 56 (1985) 220-226.