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A method for the determination of K shell fluorescence yields using photoionization
Journal of Quantitative Spectroscopy & Radiative Transfer 74 (2002) 69 – 74
www.elsevier.com/locate/jqsrt
A method for the determination of K shell )uorescence yields using photoionization Sabriye Seven K.K. Education Faculty, Department of Physics, Atarturk University, 25240 Erzurum, Turkey Received 4 May 2001; accepted 23 November 2001
Abstract K shell )uorescence yields were measured for Sr, Y, Zr, Nb, Mo, Ru, Pd, Ag, In, Sb, Cs, and Pr using a germanium detector. The targets were excited by 59:5 keV -rays from a 241 Am radioactive source of strength 400 MBq. The results obtained were compared with the theoretical predictions, semiempirical estimates and earlier results obtained by other methods. ? 2002 Elsevier Science Ltd. All rights reserved. Keywords: Photoionization; X-ray )uorescence; Fluorescence yield
1. Introduction The )uorescence yield of an atomic shell or subshell is deBned as the probability that a vacancy in that shell or subshell is Belded through a radiative transition. The )uorescence yield of a shell is equal to the number of photons emitted when vacancies in the shell are Beld, divided by the number of primary vacancies in the shell. Fluorescence yield values play an important role in a variety of Belds such as atomic physics, X-ray )uorescence analysis, health physics and industry. In addition )uorescence yield measurements provide an indirect check on physical parameters, such as photoelectric cross section, jump ratios and X-ray emission rates. Experimental and theoretical K shell )uorescence yields have been reported by diCerent authors [1–18]. Bambynek et al. [1] Btted selected experimental values of K, L and M shell )uorescence yields. Hubbel et al. [2] reviewed K, L and higher atomic shell X-ray )uorescence yields covering the period 1978–1993. In that review an annotated bibliography of X-ray )uorescence yield measurements, analysis, Bts and tables for 1978–1993 and comparisons of the )uorescence yields, !K ; $L and $M based on measurements and on theoretical models are also given. Also values of !K ; $L and $M Btted to standard empirical parametric formulations and selected well characterized measured !K ; $L and $M results restricted to the period 1978–1993 are listed. Krause [3] determined K shell and L1 ; L2 and L3 subshell )uorescence yields for all elements in the range 5 6 Z 6 110. Theoretical values of !K were obtained for various elements by McGuire [4,5], Walters and Bhala 0022-4073/02/$ - see front matter ? 2002 Elsevier Science Ltd. All rights reserved. PII: S 0 0 2 2 - 4 0 7 3 ( 0 1 ) 0 0 2 3 9 - 4
70
S. Seven / Journal of Quantitative Spectroscopy & Radiative Transfer 74 (2002) 69 – 74
[6], Kostroun et al. [7] and Chen et al. [8] by using diCerent approaches. In recent years K shell )uorescence yields for many elements have been measured [9 –18]. Hartl and Hammer [9] and Casnati et al. [13] measured K shell )uorescence yield of Ge, Takiue [11] those of Ag and In, Nasr et al. [10], Arora et al. [12] and Balakrishna et al. [16] those of intermediate Z elements, Sidhu et al. [14] those of As, Cs, Pr, Eu, Dy, Tm, Lu, Ta and Hg, Pious et al. [15] those of Fe, Cu, Zn, Ge and Mo elements, Horakeri et al. [17] those of Pb, Ta, Dy, Eu, Pr elements and Durak [18] those of Zr, Mo, Ag, Sn, Cs, Ba, Ce, Nd, Gd, Dy, Er, Yb and Ho. In the present work, K shell )uorescence yields of 12 elements (Sr, Y, Zr, Nb, Mo, Ru, Pd, Ag, In, Sb, Cs and Pr) were measured by using photoionization. The targets were ionized using 59:5 keV -rays from 241 Am (100 mCi) and emitted K X-rays were detected with a HpGe. 2. Experiment The experimental set-up is shown in Fig. 1. The experiments were carried out using a Bltered point source Am-241 (100 mCi) which emits monoenergetic (59:5 keV) -rays. Gamma rays of 26:4 keV and Np L X-rays coming from Am-241 are completely (∼ 99:99%) Bltered out with the help of graded Blter made Fe, Pb and Al. Spectroscopically pure (purity better than 99.9%) circular targets of thickness from 100 to 200 g cm−2 have been used for the measurements. All the targets have K edge energies lower than 59:5 keV. The )uorescence X-rays produced due to the interactions of the incoming photons with K shell electrons of the target elements are measured with an Enertec EGPX-R 200 high purity Ge detector have resolution 230 eV at 5:9 keV Mn K line and coupled with an ND 66B multichannel analyser system. The detector was also placed in a shield (made from Pb, Fe and Al) to minimize detection of radiations coming directly from the source and those scattered from the surroundings. A Btted spectrum of Ag K lines is shown in Fig. 2. The experimental K shell )uorescence yields were measured using the following equation: sec 1 + ( 2 = 1 ) sec 2 IK !K = ; (1) I0 GfK 1 − exp[ − ( 1 sec 1 + 2 sec 2 )tK ] where IK is sum of the K and K X-ray counting rate from the target of elements under study, I0 G is intensity of photons falling on the portion of target visible to the detector, is the detector ePciency at the K X-ray energy, fK is the fraction of the incident -ray )ux that ionizes the K shell. 1 and 2 are the total attenuation coePcients (cm2 g−1 ) at the energy of incident photons and emitted characteristic X-rays of the sample, respectively, taken from the tables of Hubbell and co-workers [19]. 1 and 2 are angles of incident photons and emitted X-rays with respect to the normal at the surface of the sample. tK is thickness of the sample under investigation. I0 G was evaluated by measuring the L X-ray yields from Th and U. The weighted average of I0 G values obtained for each Li X-ray (i = ; ; ) from Th and U was taken. The detector ePciency was measured using 241 Am; 133 Ba and 137 Cs radioisotope testing sources according to an earlier method [20]. I0 G was obtained using the expression I Li ; (2) I0 G = Li Li tLi where Li is Li X-ray production cross section of the element (Th and U) at an excitation energy of 59:5 keV, Li is the absorption correction factor of the target and t is the thickness of the target.
S. Seven / Journal of Quantitative Spectroscopy & Radiative Transfer 74 (2002) 69 – 74
Counts (a.u)
1400
220
240
260
280
300
71
320
1400
1200
1200
1000
1000
800
800
600
600
400
400
200
200
220
240
260
280
300
320
Channel
Fig. 1. Experimental set-up.
Fig. 2. A typical K X-ray spectrum of Ag.
4000 3500
Lα
Counts Per channel
3000 2500 2000
Lβ
1500 1000 Lγ 500 L 0 150
200
250
300
350
Channel
Fig. 3. A typical L X-ray spectrum of U.
A Btted spectrum of U L lines is shown in Fig. 3. The values of L ; L and L X-ray production cross section for Th and U are calculated from theoretical values of L subshell photoionization cross sections [21], radiative decay rates [22], semiempirically Btted values of )uorescence yields [3] and Coster–Kronig transition probabilities [3] using following relations: L = [1 (f13 + f12 f23 ) + 2 f23 + 3 ]!3 F3 ;
(3)
L = 1 !1 F1 + (1 f12 + 2 )!2 F2 + [3 + 2 f23 + 1 (f13 + f23 f12 )]!3 F3 ;
(4)
L = 1 !1 F1 + (2 + 1 f12 )!2 F2 ;
(5)
72
S. Seven / Journal of Quantitative Spectroscopy & Radiative Transfer 74 (2002) 69 – 74
Table 1 K X-ray )uorescence yields of Sr, Y, Zr, Nb, Mo, Ru, Pd, Ag, In, Sb, Cs and Pr
Element
38
Present work
Fit values Ref. [2]
Ref. [3]
Sr Y 40 Zr 41 Nb 42 Mo
0:675 ± 0:034 0:713 ± 0:036 0:736 ± 0:037 0:765 ± 0:038 0:766 ± 0:038
0.665 0.685 0.705 0.724 0.742
0.690 0.710 0.730 0.747 0.765
44
Ru Pd 47 Ag 49 In 51 Sb 55 Cs
0:782 ± 0:039 0:781 ± 0:039 0:815 ± 0:041 0:853 ± 0:043 0:855 ± 0:043 0:869 ± 0:043
— 0.807 0.822 0.848 0.872 0.912
0.794 0.820 0.831 0.853 0.870 0.897
59
0:875 ± 0:044
0.941
0.917
39
46
Pr
Earlier experimental
Theoretical Ref. [5]
Ref. [7]
Ref. [8]
— — 0.705 — 0.740 0.758 — — 0.822 — — 0.913 0.899 0.916 0.930
— — 0.740 — — — 0.806 — 0.842 — — —
0.702 0.722 0.721 0.759 0.776
— — 0.732 — 0.765
0.807 0.833 0.844 0.865 — —
— — 0.830 — — —
—
—
—
[18] [18] [15] [18] [18] [14] [17] [14]
where 1 ; 2 and 3 are L subshell photoionization cross sections of element at 59:5 keV. !1 ; !2 and !3 are L subshell )uorescence yields. f12 ; f13 and f23 are intra L shell Coster–Kronig transition probabilities, Fs are fractional radiative decay rates, i.e. F3 is the fraction of L3 subshell X-rays which contributes to the L peak of the X-ray spectrum of an element. In Eqs. (1) and (2) IK and ILi values are determined from the photopeak areas for K and Li X-ray recorded at the same counting geometry. The spectra were analyzed using a quantitative X-ray analysis computer code analysis of X-ray spectra for iterative least-squares Btting (AXIL) [23–25]. In Eq. (2) Li has been calculated by using 1 − exp[ − ( inc =cos 1 + emt =cos 2 )tL ] Li = ; (6) ( inc =cos 1 + emt =cos 2 )tL where inc and emt are the total attenuation coePcients (cm2 g−1 ) at the energy of incident photons and emitted characteristic X-rays of the target [19], respectively. 1 and 2 are angles of incident photons and emitted X-rays with respect to the normal at the surface of the sample and t is the thickness of the target. For each target was determined in several trials to obtain uncertainty. The present experimental values of !K are the weighted average values, taken from 10 trials for each of the targets. 3. Results and discussion The experimental results for K shell )uorescence yields are given in Table 1. In addition, the present and other results were plotted versus atomic number and shown in Fig. 4. It can be seen from Table 1 and Fig. 4 that for elements with low atomic number the present results are in
S. Seven / Journal of Quantitative Spectroscopy & Radiative Transfer 74 (2002) 69 – 74
73
Fig. 4. K shell )uorescence yield versus atomic number.
good agreement, within the experimental uncertainties, with the earlier experimental and theoretical reports but for the elements high atomic numbers present values are lower than others. However the range in high atomic number present experimental values are in agreement within the experimental uncertainties with one of the least of other experimental results yet. This method was used for the Brst time for measuring K shell )uorescence yields. In the method, the values !K are independent of the primary photon )ux and the source-target-detector geometry factor because I0 G was experimentally measured. This case proves that K shell )uorescence yield (!K ) can be determined more accurately as experimentally. The error in the measured K shell )uorescence yields is estimated to be 5% for this method. This error arises due to the uncertainties in various physical parameters, namely the error in the evaluation of the area under the K X-ray peaks (2%), eCective incident photon )ux (3%), target thickness (2%) and detector ePciency (3%). The method described above may be used to study K shell )uorescence yields of higher Z elements and higher shell )uorescence yields by employing a high-resolution detector such as HpGe, Ge(Li) or Si(Li). References [1] Bambynek W, Crasemann B, Fink RW, Freund HU, Mark H, Swift CD, Price RE, Rao PV. Rev Mod Phys 1972;44:716. [2] Hubbell JH, Trehan PN, Singh N, Chand B, Mehta D, Garg ML, Garg RR, Singh S, Puri S. J Phys Chem Ref Data 1994;23:339. [3] Krause MO. J Phys Chem Ref Data 1979;8:307. [4] McGuire EJ. Phys Rev 1969;185:1. [5] McGuire EJ. Phys Rev A 1970;2:273. [6] Walters DL, Bhalla CP. Phys Rev A 1971;3:1919. [7] Kostroun VO, Chen MH, Crasemann B. Phys Rev A 1971;3:533. [8] Chen MH, Crasemann B, Mark H. Phys Rev A 1980;21:436. [9] Hartl W, Hammer JW. Z Phys A 1976;279:135. [10] Al-Nasr IA, Jabr IJ, Al-Saleh KA, Saleh NS. Appl Phys A 1987;43:71. [11] Takiue M, Ishikawa H. Nucl Instrum Methods 1980;173:391.
74 [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25]
S. Seven / Journal of Quantitative Spectroscopy & Radiative Transfer 74 (2002) 69 – 74 Arora SK, Allawadhi KL, Sood BS. Phys BC 1981;111 C:71. Casnati E, Tartari A, Baraldi C, Napoli G. J Phys B 1984;17:2413. Sidhu NPS, Grewal BS, Sahota HS. X-Ray Spectrom 1988;17:29. Pious JK, Balakrishna KM, Lingappa N, Siddappa K. J Phys B 1992;25:1155. Balakrishna KM, Nayak NG, Lingappa N, Siddappa K. J Phys B 1994;27:715–20. Horakeri LD, Hanumaiah B, Thontadarya SR. X-Ray Spectrom 1997;26:69. Durak R. Phys Scr 1998;58:111. Hubbell JH, Seltzer SM. Report, No. NISTIR-5632, 1995, unpublished. Cohen DD. Nucl Instrum Methods 1980;21:111. ScoBeld JH, Lawrence Livermore Laboratory (UCRL) Report, No. 513626, University of California Livermore, CA, 1973, unpublished. ScoBeld JH. Phys Rev A 1969;179:9. Van Espen P, Nulles H, Adams F. Nucl Instrum Methods 1977;142:243. Van Espen P, Nulles H, Adams F. Nucl Instrum Methods 1977;145:579. Van Espen P, Nulles H, Maenhaut W. In: Newburry DE, editor. Microbeam analysis. San Francisco: San Francisco Press, 1979. p. 265.
www.elsevier.com/locate/jqsrt
A method for the determination of K shell )uorescence yields using photoionization Sabriye Seven K.K. Education Faculty, Department of Physics, Atarturk University, 25240 Erzurum, Turkey Received 4 May 2001; accepted 23 November 2001
Abstract K shell )uorescence yields were measured for Sr, Y, Zr, Nb, Mo, Ru, Pd, Ag, In, Sb, Cs, and Pr using a germanium detector. The targets were excited by 59:5 keV -rays from a 241 Am radioactive source of strength 400 MBq. The results obtained were compared with the theoretical predictions, semiempirical estimates and earlier results obtained by other methods. ? 2002 Elsevier Science Ltd. All rights reserved. Keywords: Photoionization; X-ray )uorescence; Fluorescence yield
1. Introduction The )uorescence yield of an atomic shell or subshell is deBned as the probability that a vacancy in that shell or subshell is Belded through a radiative transition. The )uorescence yield of a shell is equal to the number of photons emitted when vacancies in the shell are Beld, divided by the number of primary vacancies in the shell. Fluorescence yield values play an important role in a variety of Belds such as atomic physics, X-ray )uorescence analysis, health physics and industry. In addition )uorescence yield measurements provide an indirect check on physical parameters, such as photoelectric cross section, jump ratios and X-ray emission rates. Experimental and theoretical K shell )uorescence yields have been reported by diCerent authors [1–18]. Bambynek et al. [1] Btted selected experimental values of K, L and M shell )uorescence yields. Hubbel et al. [2] reviewed K, L and higher atomic shell X-ray )uorescence yields covering the period 1978–1993. In that review an annotated bibliography of X-ray )uorescence yield measurements, analysis, Bts and tables for 1978–1993 and comparisons of the )uorescence yields, !K ; $L and $M based on measurements and on theoretical models are also given. Also values of !K ; $L and $M Btted to standard empirical parametric formulations and selected well characterized measured !K ; $L and $M results restricted to the period 1978–1993 are listed. Krause [3] determined K shell and L1 ; L2 and L3 subshell )uorescence yields for all elements in the range 5 6 Z 6 110. Theoretical values of !K were obtained for various elements by McGuire [4,5], Walters and Bhala 0022-4073/02/$ - see front matter ? 2002 Elsevier Science Ltd. All rights reserved. PII: S 0 0 2 2 - 4 0 7 3 ( 0 1 ) 0 0 2 3 9 - 4
70
S. Seven / Journal of Quantitative Spectroscopy & Radiative Transfer 74 (2002) 69 – 74
[6], Kostroun et al. [7] and Chen et al. [8] by using diCerent approaches. In recent years K shell )uorescence yields for many elements have been measured [9 –18]. Hartl and Hammer [9] and Casnati et al. [13] measured K shell )uorescence yield of Ge, Takiue [11] those of Ag and In, Nasr et al. [10], Arora et al. [12] and Balakrishna et al. [16] those of intermediate Z elements, Sidhu et al. [14] those of As, Cs, Pr, Eu, Dy, Tm, Lu, Ta and Hg, Pious et al. [15] those of Fe, Cu, Zn, Ge and Mo elements, Horakeri et al. [17] those of Pb, Ta, Dy, Eu, Pr elements and Durak [18] those of Zr, Mo, Ag, Sn, Cs, Ba, Ce, Nd, Gd, Dy, Er, Yb and Ho. In the present work, K shell )uorescence yields of 12 elements (Sr, Y, Zr, Nb, Mo, Ru, Pd, Ag, In, Sb, Cs and Pr) were measured by using photoionization. The targets were ionized using 59:5 keV -rays from 241 Am (100 mCi) and emitted K X-rays were detected with a HpGe. 2. Experiment The experimental set-up is shown in Fig. 1. The experiments were carried out using a Bltered point source Am-241 (100 mCi) which emits monoenergetic (59:5 keV) -rays. Gamma rays of 26:4 keV and Np L X-rays coming from Am-241 are completely (∼ 99:99%) Bltered out with the help of graded Blter made Fe, Pb and Al. Spectroscopically pure (purity better than 99.9%) circular targets of thickness from 100 to 200 g cm−2 have been used for the measurements. All the targets have K edge energies lower than 59:5 keV. The )uorescence X-rays produced due to the interactions of the incoming photons with K shell electrons of the target elements are measured with an Enertec EGPX-R 200 high purity Ge detector have resolution 230 eV at 5:9 keV Mn K line and coupled with an ND 66B multichannel analyser system. The detector was also placed in a shield (made from Pb, Fe and Al) to minimize detection of radiations coming directly from the source and those scattered from the surroundings. A Btted spectrum of Ag K lines is shown in Fig. 2. The experimental K shell )uorescence yields were measured using the following equation: sec 1 + ( 2 = 1 ) sec 2 IK !K = ; (1) I0 GfK 1 − exp[ − ( 1 sec 1 + 2 sec 2 )tK ] where IK is sum of the K and K X-ray counting rate from the target of elements under study, I0 G is intensity of photons falling on the portion of target visible to the detector, is the detector ePciency at the K X-ray energy, fK is the fraction of the incident -ray )ux that ionizes the K shell. 1 and 2 are the total attenuation coePcients (cm2 g−1 ) at the energy of incident photons and emitted characteristic X-rays of the sample, respectively, taken from the tables of Hubbell and co-workers [19]. 1 and 2 are angles of incident photons and emitted X-rays with respect to the normal at the surface of the sample. tK is thickness of the sample under investigation. I0 G was evaluated by measuring the L X-ray yields from Th and U. The weighted average of I0 G values obtained for each Li X-ray (i = ; ; ) from Th and U was taken. The detector ePciency was measured using 241 Am; 133 Ba and 137 Cs radioisotope testing sources according to an earlier method [20]. I0 G was obtained using the expression I Li ; (2) I0 G = Li Li tLi where Li is Li X-ray production cross section of the element (Th and U) at an excitation energy of 59:5 keV, Li is the absorption correction factor of the target and t is the thickness of the target.
S. Seven / Journal of Quantitative Spectroscopy & Radiative Transfer 74 (2002) 69 – 74
Counts (a.u)
1400
220
240
260
280
300
71
320
1400
1200
1200
1000
1000
800
800
600
600
400
400
200
200
220
240
260
280
300
320
Channel
Fig. 1. Experimental set-up.
Fig. 2. A typical K X-ray spectrum of Ag.
4000 3500
Lα
Counts Per channel
3000 2500 2000
Lβ
1500 1000 Lγ 500 L 0 150
200
250
300
350
Channel
Fig. 3. A typical L X-ray spectrum of U.
A Btted spectrum of U L lines is shown in Fig. 3. The values of L ; L and L X-ray production cross section for Th and U are calculated from theoretical values of L subshell photoionization cross sections [21], radiative decay rates [22], semiempirically Btted values of )uorescence yields [3] and Coster–Kronig transition probabilities [3] using following relations: L = [1 (f13 + f12 f23 ) + 2 f23 + 3 ]!3 F3 ;
(3)
L = 1 !1 F1 + (1 f12 + 2 )!2 F2 + [3 + 2 f23 + 1 (f13 + f23 f12 )]!3 F3 ;
(4)
L = 1 !1 F1 + (2 + 1 f12 )!2 F2 ;
(5)
72
S. Seven / Journal of Quantitative Spectroscopy & Radiative Transfer 74 (2002) 69 – 74
Table 1 K X-ray )uorescence yields of Sr, Y, Zr, Nb, Mo, Ru, Pd, Ag, In, Sb, Cs and Pr
Element
38
Present work
Fit values Ref. [2]
Ref. [3]
Sr Y 40 Zr 41 Nb 42 Mo
0:675 ± 0:034 0:713 ± 0:036 0:736 ± 0:037 0:765 ± 0:038 0:766 ± 0:038
0.665 0.685 0.705 0.724 0.742
0.690 0.710 0.730 0.747 0.765
44
Ru Pd 47 Ag 49 In 51 Sb 55 Cs
0:782 ± 0:039 0:781 ± 0:039 0:815 ± 0:041 0:853 ± 0:043 0:855 ± 0:043 0:869 ± 0:043
— 0.807 0.822 0.848 0.872 0.912
0.794 0.820 0.831 0.853 0.870 0.897
59
0:875 ± 0:044
0.941
0.917
39
46
Pr
Earlier experimental
Theoretical Ref. [5]
Ref. [7]
Ref. [8]
— — 0.705 — 0.740 0.758 — — 0.822 — — 0.913 0.899 0.916 0.930
— — 0.740 — — — 0.806 — 0.842 — — —
0.702 0.722 0.721 0.759 0.776
— — 0.732 — 0.765
0.807 0.833 0.844 0.865 — —
— — 0.830 — — —
—
—
—
[18] [18] [15] [18] [18] [14] [17] [14]
where 1 ; 2 and 3 are L subshell photoionization cross sections of element at 59:5 keV. !1 ; !2 and !3 are L subshell )uorescence yields. f12 ; f13 and f23 are intra L shell Coster–Kronig transition probabilities, Fs are fractional radiative decay rates, i.e. F3 is the fraction of L3 subshell X-rays which contributes to the L peak of the X-ray spectrum of an element. In Eqs. (1) and (2) IK and ILi values are determined from the photopeak areas for K and Li X-ray recorded at the same counting geometry. The spectra were analyzed using a quantitative X-ray analysis computer code analysis of X-ray spectra for iterative least-squares Btting (AXIL) [23–25]. In Eq. (2) Li has been calculated by using 1 − exp[ − ( inc =cos 1 + emt =cos 2 )tL ] Li = ; (6) ( inc =cos 1 + emt =cos 2 )tL where inc and emt are the total attenuation coePcients (cm2 g−1 ) at the energy of incident photons and emitted characteristic X-rays of the target [19], respectively. 1 and 2 are angles of incident photons and emitted X-rays with respect to the normal at the surface of the sample and t is the thickness of the target. For each target was determined in several trials to obtain uncertainty. The present experimental values of !K are the weighted average values, taken from 10 trials for each of the targets. 3. Results and discussion The experimental results for K shell )uorescence yields are given in Table 1. In addition, the present and other results were plotted versus atomic number and shown in Fig. 4. It can be seen from Table 1 and Fig. 4 that for elements with low atomic number the present results are in
S. Seven / Journal of Quantitative Spectroscopy & Radiative Transfer 74 (2002) 69 – 74
73
Fig. 4. K shell )uorescence yield versus atomic number.
good agreement, within the experimental uncertainties, with the earlier experimental and theoretical reports but for the elements high atomic numbers present values are lower than others. However the range in high atomic number present experimental values are in agreement within the experimental uncertainties with one of the least of other experimental results yet. This method was used for the Brst time for measuring K shell )uorescence yields. In the method, the values !K are independent of the primary photon )ux and the source-target-detector geometry factor because I0 G was experimentally measured. This case proves that K shell )uorescence yield (!K ) can be determined more accurately as experimentally. The error in the measured K shell )uorescence yields is estimated to be 5% for this method. This error arises due to the uncertainties in various physical parameters, namely the error in the evaluation of the area under the K X-ray peaks (2%), eCective incident photon )ux (3%), target thickness (2%) and detector ePciency (3%). The method described above may be used to study K shell )uorescence yields of higher Z elements and higher shell )uorescence yields by employing a high-resolution detector such as HpGe, Ge(Li) or Si(Li). References [1] Bambynek W, Crasemann B, Fink RW, Freund HU, Mark H, Swift CD, Price RE, Rao PV. Rev Mod Phys 1972;44:716. [2] Hubbell JH, Trehan PN, Singh N, Chand B, Mehta D, Garg ML, Garg RR, Singh S, Puri S. J Phys Chem Ref Data 1994;23:339. [3] Krause MO. J Phys Chem Ref Data 1979;8:307. [4] McGuire EJ. Phys Rev 1969;185:1. [5] McGuire EJ. Phys Rev A 1970;2:273. [6] Walters DL, Bhalla CP. Phys Rev A 1971;3:1919. [7] Kostroun VO, Chen MH, Crasemann B. Phys Rev A 1971;3:533. [8] Chen MH, Crasemann B, Mark H. Phys Rev A 1980;21:436. [9] Hartl W, Hammer JW. Z Phys A 1976;279:135. [10] Al-Nasr IA, Jabr IJ, Al-Saleh KA, Saleh NS. Appl Phys A 1987;43:71. [11] Takiue M, Ishikawa H. Nucl Instrum Methods 1980;173:391.
74 [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25]
S. Seven / Journal of Quantitative Spectroscopy & Radiative Transfer 74 (2002) 69 – 74 Arora SK, Allawadhi KL, Sood BS. Phys BC 1981;111 C:71. Casnati E, Tartari A, Baraldi C, Napoli G. J Phys B 1984;17:2413. Sidhu NPS, Grewal BS, Sahota HS. X-Ray Spectrom 1988;17:29. Pious JK, Balakrishna KM, Lingappa N, Siddappa K. J Phys B 1992;25:1155. Balakrishna KM, Nayak NG, Lingappa N, Siddappa K. J Phys B 1994;27:715–20. Horakeri LD, Hanumaiah B, Thontadarya SR. X-Ray Spectrom 1997;26:69. Durak R. Phys Scr 1998;58:111. Hubbell JH, Seltzer SM. Report, No. NISTIR-5632, 1995, unpublished. Cohen DD. Nucl Instrum Methods 1980;21:111. ScoBeld JH, Lawrence Livermore Laboratory (UCRL) Report, No. 513626, University of California Livermore, CA, 1973, unpublished. ScoBeld JH. Phys Rev A 1969;179:9. Van Espen P, Nulles H, Adams F. Nucl Instrum Methods 1977;142:243. Van Espen P, Nulles H, Adams F. Nucl Instrum Methods 1977;145:579. Van Espen P, Nulles H, Maenhaut W. In: Newburry DE, editor. Microbeam analysis. San Francisco: San Francisco Press, 1979. p. 265.