K-shell Fluorescence Yield Research Articles

Measurement of K-shell fluorescence yields for Ba, Ce, Nd, Gd, Dy, Er and Yb using radioisotope XRF

K-shell fluorescence yields were measured for Ba, Ce, Nd, Gd, Dy, Er and Yb by using a Ge(Li) detector employing the reflection geometry. The target atoms were excited by 122 keV γ-rays from 57Co radioactive source of strength 100 mCi. The experimental results are compared with the literature experimental values, theoretical predictions and the semiempirical fits.

Evaluation of atomic shell data

Experimental and theoretical values of the following constants have been collected from the literature and evaluated: K-shell fluorescence yield (ω K) and mean L-shell fluorescence yield ( ω L), ratios of X-ray emission probabilities [ x = p(K β)/ p(K α), and p(K α2)/ p(K α1)], ratios of emission probabilities of Auger electrons [ u = p(KLX)/ p(KLL), v = p(KXY)/ p(KLL)], and the vacancy transfer coefficient ( n KL). Relations for the emission probabilities of complementary Auger electrons (for example, KLM and KML) and the assumption of equal probability ratios in processes that are inverse to each other have been used to show that u and v can be expressed in terms of x by u = 2 x and v = x 2; the coefficient n KL becomes simply (2 − ω K)/(1 + x).

Measurement of PKωK in the decay of 65Zn and the K-shell fluorescence yield of copper

The product of the K-capture probability, P K , and the K-shell fluorescence yield, ω K of copper, P K ω K , in the decay of 65Zn was measured to be 0.398 ± 0.002. A gas-flow proportional counter was used to measure the x-rays and a NaI(T1) detector to measure the γ-rays. P K ω K was derived from the coincidences between x- and γ-rays. From the measured value of P K ω K and the theoretical K-capture probability P K = 0.880 ± 0.002, the K-shell fluorescence yield ω K = 0.452 ± 0.003 for copper is deduced.

Measurement of the K-shell fluorescence yield of Ca and K with a windowless Si(Li) detector

Measurements of the fluorescence yield of calcium and potassium with a windowless Si(Li) detector have been performed. In metallic layers K-shell vacancies were produced by photo effect with a 55Fe source. The values obtained are ω K(CA) = (0.164 ± 0.004) and ω K(K) = (0.144 ± 0.004). For potassium this is the first experimental value reported.

Determination of the Manganese K-shell Fluorescence Yield from the 55Fe Decay

The manganese K-shell fluorescence yield (ωK) in the 55Fe decay for two thermally evaporated sources was measured using absolute measurement methods for the activity and the K X-ray emission rate with the national primary standard at VNIIM.The mean value obtained is ωK = 0.312 ± 0.003 which agrees with a semiempirical value of ωK = 0.314 ± 0.023 within the limits of measurement uncertainty.

K-shell fluorescence yields of silicon and germanium by detector escapes

Evaluating the K-shell fluorescence yield of an X-ray detector material like Si or Ge from the escape to parent peak ratio is essentially an integration problem; e.g., side wall effects make a contribution of the order of 1% for uncollimated beams. The transition from atomic X-ray fluorescence to detector emission is physically governed by relative absorption coefficients, and it is the uncertainty in these values which restricts the numerical reliability of the results: omega K.Si=0.0481+or-0.0014 and omega K,Ge=0.532+or-0.016. Both the values with their associated error limits are not sufficient to decide whether effects of the outer-shell configuration are numerically relevant.

Determination of PKvalues to the 172, 103 and 97 keV levels and the fluorescence yield ωKof Eu after electron capture by153Gd

From an analysis of K X-ray- gamma -ray sum peaks observed with an intrinsic Ge detector the K-capture probabilities (PK) to the 172, 103 and 97 keV levels in the decay of 153Gd have been determined; these yield an electron-capture energy QEC=245+or-2. The K-capture probability to the 172 keV level differs significantly from that found in the literature. With these results the K-shell fluorescence yield of Eu is omega K=0.935+or-0.019.

Experimental K-shell fluorescence yield of monocrystalline germanium

The result of an experimental evaluation of the K-shell fluorescence yield, omega K, of monocrystalline Ge is reported. The procedure makes use of the information contained in the escape peaks which are present in the characteristic X-ray spectra given by an HP Ge detector. Details of the experimental methodology, peak area evaluations and uncertainty treatments are described. A value omega K=0.549+or-0.011 is obtained and compared with recent values obtained from experiment, theory, interpolation or normalisation. The authors consider the effects of the outer-shell configuration and the use of theoretical photoelectric cross section values.

A new method of measuring the K-shell fluorescence yield of As

A new method for the determination of the K-shell fluorescence yield from the analysis of sum peaks observed with a high-resolution intrinsic Ge semiconductor detector in the decay of 75Se is described. The value found is omega K(As)=0.574(18), which is in agreement with the fitted value of Bambynek et al. (1977).

K-shell fluorescence yield of Cs

A new technique has been developed in the measurement of the K-shell fluorescence yield of cesium from the analysis of the sum peaks observed with a high resolution intrinsic Ge detector. The value found is ..omega../sub k/(Cs) = 0.896(16), which is in good agreement with the fitted value of Bambynek et al.

Measurement of theK-shell fluorescence yield of13Al,20Ca,23V and25Mn for vacancies produced by the relativistic electron impact

The K-shell fluorescence yield of Al, Ca, V and Mn has been measured by bombarding thin solid targets of 0.5–4.0μg/cm2 on 6–10μg/cm2 carbon backing with relativistic electrons of 30 and 60 MeV and by simultaneous detection of the x-ray and Auger yield by means of a Si(Li) detector and an electrostatic electron spectrometer, respectively. While the values obtained for25Mn (ωK=0.310−0.020+0.023) and23V(ωK=0.252−0.018+0.020) agree within their accuracy with known experimental and theoretical data, are the values of20Ca (ωK=0.127−0.011+0.013) and13Al(ωK=0.027±0.005) lower than experimental or recommended empirical values.

Ne K-shell fluorescence yield in collisions between Ne-atoms and Ne-ions at 0.6-2.3 MeV

Ne K-shell fluorescence yields, ω + K in 0.6-1.9 MeV Ne +−Ne and ω ++ K in 1.3-2.3 MeV Ne ++−Ne collisions, have been obtained by observing the Ne-K X-ray production cross sections and combining them with the Ne-K Auger electron production cross sections by Stolterfoht et al. [2]. The results show a linear increase with increasing collision energy, and run from 0.02 to 0.05. A projectile charge dependence of the fluorescence yield has not been observed within experimental uncertainty. In the present violent collision region, the degree of multiple ionization still increases with increasing collision energies, and the atomic configurations involved are believed to be represented by (1s 0, 1 2s 0, 1 2p 2, 3, 4).

Statistical scaling of C and O K-shell fluorescence yields

Relative C and O K-shell fluorescence yields, computed from statistically scaled radiative and nonradiative rates for various molecules, show good agreement with experimental fluorescence yields for CH 4, C 2H 2, C 2H 4, C 2H 6, CO, CO 2, and CF 4 (C-bearing), and O 2, CO, CO 2, H 2O (O-bearing) gases.

RelativisticK-shell Auger rates, level widths, and fluorescence yields

Systematic relativistic (Dirac-Hartree-Slater) calculations of atomic K-shell Auger transition probabilities are reported for 25 elements with Z between 18 and 96, inclusive. K-level Auger widths are found to be enhanced by relativistic effects, while total K-level widths are reduced. Relativistic theoretical K-shell fluorescence yields are in excellent agreement with experiment. Theoretical relative intensities of K-LX Auger transitions in heavy elements, calculated in j-j coupling, agree well with measurements; for low Z, configuration interaction and intermediate coupling must apparently be included.

Metastable X-ray emission following violent Cl13+–Ne collisions

Abstract For Cl 13+ bombardment the K X-ray transition from the metastable 4 P state in Li-Like Ne is clearly resolved from an overlapping Be-like line. Previously measured K-shell fluorescence yields are corrected for this overlap. The detected rate of metastable to prompt X-ray emission from Li-like Ne is observed to vary with projectile energy.

Dependence of K-shell fluorescence yields on multiplet states of neon

The K-shell fluorescence yields are calculated to be equal to 0.013 and 0.028 respectively for 3P and 1P multiplet states of 1s 1 2s 2 2p 5 configuration of neon. This observation can significantly effect analyses of ion-atom collision experiments where in X-ray production cross-sections are measured.

Effects of multiple ionization on K-shell fluorescence yield transition energies and intensity ratios for argon

Theoretical calculations of ω K, changes in the K α and K β X-ray energies and ratios of K β and K α intensities for multiply-ionized argon are presented using the nonrelativistic Hartree-Fock-Slater atomic model.

Precision determination of high-Z K-shell fluorescence yields from195Au,207Bi, and235Np decays

A new method utilizing a cooled, high resolution, windowless Si(Li) x-ray and Auger electron detector has been developed for the accurate measurement of high-Z K-shell fluorescence yields. With this method, values of theK-fluorescence yield ω k have been determined with high accuracy atZ=78, 82, and 92 from the radioactive decay of carrier-free195Au,207Bi, and235Np, respectively. The values of ω k are 0.968±0.008, 0.972±0.008, and 0.970±0.005, respectively where the error limits represent 95% confidence. In addition, relativeK-Auger electron group intensities atZ=92 were measured and found to be(K-LL)∶(K-LX)∶(K-XY)=100∶(65.2±6.0)∶ (8.1±0.8). The experimental results for ω k are compared with the relativistic calculations of Bhalla, Ramsdale and, Rosner, and satisfactory agreement is found.

The influence of molecular environment on the K-shell fluorescence yield of carbon in small molecules

The cross sections for carbon-K X-ray emission have been measured for 0.5–4 keV electrons incident on CH 4, C 2H 6, C 3H 8, C 2H 2, C 2H 4, CO and CO 2. It is found that, although the cross sections per carbon atom show the same dependence on the incident electron energy, they differ in magnitude by up to 35%. This is interpreted as an effect of the molecular environment on the fluorescence yield.

Investigation of the decay 73As → 73Ge

Abstract The γ-ray, K X-ray and conversion electron spectra produced by electron capture in 73 As have been investigated using delayed coincidence techniques. Values of 0.57±0.10 sec and 2.94±0.04 μsec were derived for the half-lives of the 66.8 keV and 13.5 keV levels in 73 Ge. The transitions at 53.3 keV and 13.5 keV were confirmed to be M2 retarded and E2 enhanced respectively. An attempt was made to interpret these results in terms of core excitation or cooperative properties of the nuclear levels. Results were also obtained for the K-capture fraction in 73 As and for the K-shell fluorescence yield in germanium.