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Molecular mass spectrum obtained in the presence of luminophors
Ituernariotzul
JoutnuI
of Mars
Specrronxerty
Elsevier Scientific Publishing Company,
MOLECULAR MASS OF LUMINOPHORS
GR.
und Ion
SPECTRUM
293
PIt_wics. 44 ( 1982) 293-295
Amsterdam
-
Printed in The Netherlands
OBTAINED
IN THE
PRESENCE
ALEXANDRU
Ittsrirure ftf Physics (First
utd
received 2 March
Nrrcleur
Engitteerittg.
BIK?IU~~~SI. P. 0.
Box
52l)b
(Rutmmiu)
1982: in final form 7 June 19S2)
ABSTRACT It is shown that the mass spwtrum of whrptane contains considerable amounts of collision ions.
obtained
in the prcsaxx
of luminophors
INTRODUCTION It is known that in many cases the molecular mass spectra contain. in reduced intensity_ collision ions that occur due to the addition of fragment and molecular ions to neutral molecules_ forming ions heavier than molecular ions. The collision ion peak intensity depends on the pressure in a more pronounced manner than the rest of the peaks. a fact that allows their differentiation with respect to normal peaks from a sample_ In this paper it is shown that, when a luminophor of the re-combined radical type is deposited on the ionization chamber walls of the mass spectrometer. the intensity of the collision ions increases considerably-
THEORY
We presume that the ion I + interacts with the neutral molecule M. As a result the addition process appears wherein the combination ion formed is in an excited condition according to the reaction M+I+
+(++I)+*
(1)
Further, the process develops may be formed again
in two directions:
the component
(M+I)+*-MM++ or electromagnetic
particles (2)
waves (light) are emitted
(M + I)+ * -+(M+I)++hv 0020-7381/82/0000-OOOO/SO2.75
(3) 6
1982 Elsevier Scientific Publishing Company
294
the collision ion decaying to the fundamental state. The theoretical considerations and experiment data show that the ratio of reaction (3) and (2) probabilities is of the order 1:20. If one takes into account reduced pressure existing in the ionization chamber. reaction ( 1) probability is also reduced and one can understand why the intensity of the collision ions is smali. If the excited ion (M + I)+ * interacts with a third particle that is capable of absorbing the considered excitation energy, the formation probability of the collision ions increaeses, but the three-body interaction probability is reduced. The three-body interaction probability is increased by about two orders of magnitude if the third body consists of a luminescent adsorbent that is deposited on the walls of the mass spectrometer ionization chamber. EXPERIMENTAL
DATA
The best results have been obtained in the case where the luminescent adsorbent _is of the recombined radical (RRL) type. These have the property of transforming the excitation energy of the ion (M + I)* * into luminous energy [ 11. Luminophors of type CaO have been used because they are very effective energy absorbers [2]. The mass spectrum of n-heptane obtained in the presence of a luminophor is presented (C-C bonds only) in Fig. 1, where a considerable intensity of ions having a mass greater than 99 (broken lines) is observed. These are the collision ions. RRL luminophors were deposited in the ionisation chamber by means of an organic solvent [3]. In the case when RRL luminophors are absent. the n-heptane mass spectrum is identical with that presented in ref. 4 which signifies that no three-body collision ions are occurring. From o comparison oi the n-heptane mass spectra (the C-C and C’H
I
i i i
P
70/-
i 0
Illu
i
0
i i i
p 15 29 43 57
I,
P
71
?
PI. .
135 99
?;. : i 1 I
I : I ; ; I
113 ?27 14? m/z
x20
t f ‘,
p *
9.
0.
?.% 759 I83 N7 m
_
Fig. 1. The mass spectrum of n-heprane in the presence of CaO luminophor.
bonds) in the presence and absence of RRL luminophors it can be seen that the disputed addition takes place mainly between neutral molecules and an ionic fragment that has previously lost one or two hydrogen atoms. We conclude that obtaining molecular mass spectra in the presence of RRL luminophors is interesting both from the point of view of the mass spectrometry as well as for a deeper understanding of luminophors. REFERENCES 1 G. Szigeti (Ed.). Proc_ Int. Conf. Luminescence_ Vols. 1 and 2. Akudemiai Kiado. 1968_ 2 F-F_ Volkenstdn. A-N_ Gorban and V-A_ Socolov. Radicalorecombinntionnnin zentzia poluprvodnicov. Nauka. Moskva. 1976. 3 A. Baczewski. .I. Efectrochem. Sot.. 112 ( 1965) I _ 4 Gr. Alexandra Int. J_ Mass Spectrom. Ion Phys.. 10 (1972/73) 39.
Budapest. luminist-
JoutnuI
of Mars
Specrronxerty
Elsevier Scientific Publishing Company,
MOLECULAR MASS OF LUMINOPHORS
GR.
und Ion
SPECTRUM
293
PIt_wics. 44 ( 1982) 293-295
Amsterdam
-
Printed in The Netherlands
OBTAINED
IN THE
PRESENCE
ALEXANDRU
Ittsrirure ftf Physics (First
utd
received 2 March
Nrrcleur
Engitteerittg.
BIK?IU~~~SI. P. 0.
Box
52l)b
(Rutmmiu)
1982: in final form 7 June 19S2)
ABSTRACT It is shown that the mass spwtrum of whrptane contains considerable amounts of collision ions.
obtained
in the prcsaxx
of luminophors
INTRODUCTION It is known that in many cases the molecular mass spectra contain. in reduced intensity_ collision ions that occur due to the addition of fragment and molecular ions to neutral molecules_ forming ions heavier than molecular ions. The collision ion peak intensity depends on the pressure in a more pronounced manner than the rest of the peaks. a fact that allows their differentiation with respect to normal peaks from a sample_ In this paper it is shown that, when a luminophor of the re-combined radical type is deposited on the ionization chamber walls of the mass spectrometer. the intensity of the collision ions increases considerably-
THEORY
We presume that the ion I + interacts with the neutral molecule M. As a result the addition process appears wherein the combination ion formed is in an excited condition according to the reaction M+I+
+(++I)+*
(1)
Further, the process develops may be formed again
in two directions:
the component
(M+I)+*-MM++ or electromagnetic
particles (2)
waves (light) are emitted
(M + I)+ * -+(M+I)++hv 0020-7381/82/0000-OOOO/SO2.75
(3) 6
1982 Elsevier Scientific Publishing Company
294
the collision ion decaying to the fundamental state. The theoretical considerations and experiment data show that the ratio of reaction (3) and (2) probabilities is of the order 1:20. If one takes into account reduced pressure existing in the ionization chamber. reaction ( 1) probability is also reduced and one can understand why the intensity of the collision ions is smali. If the excited ion (M + I)+ * interacts with a third particle that is capable of absorbing the considered excitation energy, the formation probability of the collision ions increaeses, but the three-body interaction probability is reduced. The three-body interaction probability is increased by about two orders of magnitude if the third body consists of a luminescent adsorbent that is deposited on the walls of the mass spectrometer ionization chamber. EXPERIMENTAL
DATA
The best results have been obtained in the case where the luminescent adsorbent _is of the recombined radical (RRL) type. These have the property of transforming the excitation energy of the ion (M + I)* * into luminous energy [ 11. Luminophors of type CaO have been used because they are very effective energy absorbers [2]. The mass spectrum of n-heptane obtained in the presence of a luminophor is presented (C-C bonds only) in Fig. 1, where a considerable intensity of ions having a mass greater than 99 (broken lines) is observed. These are the collision ions. RRL luminophors were deposited in the ionisation chamber by means of an organic solvent [3]. In the case when RRL luminophors are absent. the n-heptane mass spectrum is identical with that presented in ref. 4 which signifies that no three-body collision ions are occurring. From o comparison oi the n-heptane mass spectra (the C-C and C’H
I
i i i
P
70/-
i 0
Illu
i
0
i i i
p 15 29 43 57
I,
P
71
?
PI. .
135 99
?;. : i 1 I
I : I ; ; I
113 ?27 14? m/z
x20
t f ‘,
p *
9.
0.
?.% 759 I83 N7 m
_
Fig. 1. The mass spectrum of n-heprane in the presence of CaO luminophor.
bonds) in the presence and absence of RRL luminophors it can be seen that the disputed addition takes place mainly between neutral molecules and an ionic fragment that has previously lost one or two hydrogen atoms. We conclude that obtaining molecular mass spectra in the presence of RRL luminophors is interesting both from the point of view of the mass spectrometry as well as for a deeper understanding of luminophors. REFERENCES 1 G. Szigeti (Ed.). Proc_ Int. Conf. Luminescence_ Vols. 1 and 2. Akudemiai Kiado. 1968_ 2 F-F_ Volkenstdn. A-N_ Gorban and V-A_ Socolov. Radicalorecombinntionnnin zentzia poluprvodnicov. Nauka. Moskva. 1976. 3 A. Baczewski. .I. Efectrochem. Sot.. 112 ( 1965) I _ 4 Gr. Alexandra Int. J_ Mass Spectrom. Ion Phys.. 10 (1972/73) 39.
Budapest. luminist-