Der Einfluß eines elektrischen Feldes auf Level-Crossings des 6d 2 D 3/2-Zustands im TlI-Spektrum

The influence of an electric field on the energy levels of the 6d²D_3/2-state in the Tl I-spectrum was studied by measuring the shifts of level crossing signals relative to their magnetic field positions. The following values of the magnetic hyperfine constantA and the Stark parameterβ were deduced: ¦A¦=42(2) Mc/sec · g_J/0.8, ¦β¦=0.12(1) Mc/sec/(kV/cm)² · g_J/0.8 and A/β>0. Assuming that the main part of the energy shifts are caused by admixtures of the 7p²P-states the sign of the Stark parameterβ and —from the measured ratio A/β>0 —the sign of theA-factor should be negative. For electric field strength E?30 kV/cm the energy shifts of the 6d²D_3/2state are considerably greater than the hyperfine structure splitting. Therefore the case of decoupled hyperfine structure is considered.     

Stark-Effekt-Untersuchungen in der Hyperfeinstruktur der 3s 2 3d 2 D 5/2- und2 D 3/2-Terme des Al I-Spektrums

The resonance fluorescence of the transitions 3d ² D _5/2,3/2 3p ² P _3/2,1/2 in the Al I-spectrum was observed as a function of a magnetic field. Adding an electric field parallel to the magnetic field the shifts of level crossing signals caused by the Stark effect of the electric field were used to separate overlapping signals of the 3d ² D _5/2- and 3d ² D _3/2-states. The following values of the Stark parametersβ of both states and the hyperfine structure constantsA andB of the 3d ² D _3/2-states were deduced: 3d ² D _3/2∶ ¦A¦=99(1) Me/sec · g_J/0,8,B/A=?0,22(12), ¦β¦=0.45 (8) Mc/sec/(kV/cm)² · g_J,/0.8, A/β< 0 3d²D_5/2∶ ¦β¦=0.16 (4) Mc/sec/(kV/cm)² · g_J/1.2, A/β>0. Some qualitative aspects of interconfiguration mixing in the 3d²D-states are discussed.     

Resonanzstreuung von Licht in magnetischen und elektrischen Feldern zur Untersuchung der Hyperfeinstruktur des 7d 2 D 3/2-Terms im Thallium I-Spektrum

Observing the resonance fluorescence of the transition 7d ² D _3/2-6p ² P _1/2 (λ=2379 Å) in the Tl I-spectrum the level crossing technique with combined electric and magnetic fields was used to investigate the hyperfine structure and the Stark effect of the 7d ² D _3/2-state. For electric field strengthsE?25 kV/cm the Stark shifts are considerably greater than the hyperfine splitting. Therefore the crossing signals for the case of decoupled hyperfine structure could be detected. The following values of the magnetic hyperfine constantA and the Stark parameterβ were deduced: ¦A¦=55(1) Mc/sec·g _J /0.8, ¦β¦=0.20(4) Mc/sec/(kV/cm)²·g _J /0.8 andA/β>0. The widths of the signals yielded the mean lifetimeτ=2.7(5)·10^?8 sec· 0.8/g _J . Sign and values ofA andβ are discussed.     

Studies of characteristic flash X-ray lines

Level crossings obeying the selection ruleΔm=2 have been detected in the 6² P _3/2-state of both Rb⁸⁵ and Rb⁸⁷. Using the measured crossing points, the ratios of the hyperfinestructure constants to theg _J -factor are determined from a calculation for intermediate magnetic fields. The ratios areA ₈₅/g _J =6.119 (3) Mc/s,B ₈₅/g _J =6.14 (2) Mc/s,A ₈₇/g _J =20.70 (3) Mc/s,B ₈₇/g _J =2.93 (5) Mc/s. From the zero field level crossing of Rb⁸⁷ the lifetimeτ=1.14 (6) · 10^?7sec of the 6²P_3/2-state is obtained. Level crossing signals have also been observed in the presence of noble gas admixtures.     

Stark-Effekt-Untersuchungen der Hyperfeinstruktur der 5s25d2D3/2- und 5s25d2D3/2-Terme im In I-Spektrum

The level-crossing technique with combined electric and magnetic fields was used to investigate the hyperfine structure of the 5s ²5d ² D _3/2- and 5s ²6d ² D _3/2-stedes of the In I-spectrum. From the shifts of the level-crossing signals due to the Stark effect of the electric field the Stark constantsβ of both states were deduced: 5s ²5d ² D _3/2: ¦β¦=0.33(3) Mc/(kV/cm)² 5s ²6d ² D _3/2: ¦β¦=6(1) Mc/(kV/cm)². By theoretical calculations with wave functions of the Coulomb approximation one can show, that the Stark effect in both states is mainly due to admixtures of the 5s ²6p- resp.5s ²7p-configuration.     

Level-crossing-Untersuchung der Hyperfeinstruktur des angeregten 32 P 3/2- und 42 P 3/2-Zustands von Na23

The hyperfine structure of the excited 3² P _3/2- and 4² P _3/2-state of Na²³ has been investigated in a level-crossing-experiment by means of a detailed analysis of the dependence of the scattered resonance light as a function of the magnetic field. From the experimental curves the following results for the hyperfine structure constantsA andB and for the lifetimesΤ were deduced 3² P _3/2-state: 4² P _3/2-state:A=18.65(10)Mc/sA=6.006(30)g _j/1.334Mc/sB=2.82(30)Mc/sB=0.86 (9)g _j/1.334Mc/sΤ=1.60 (3) · 10^?8sΤ=6.56 (25)1.334/g_j·10^?8 s. The nuclear electric quadrupolemoment of Na²³ derived from these values isQ=0,097 · 10^?24 cm², where the Sternheimer-correction has been applied.     

Die Hyperfeinstruktur des 32P3/2-Zustands von Natrium im starken Magnetfeld

The hyperfine structure of the 3²P_3/2 State of Na²³has been measured by the optical double resonance technique in a magnetic field of 3.1 kG sufficiently strong to decouple completelyI andJ. In the case of π or (σ⁺+σ^?) excitation the double resonance signal represents the superposition curve of eight unresolved radio-frequency transitions. The dependence of the signal on the pressure of sodium vapour and the radio-frequency field strength has been studied. The analysis of the experimental curves yields for the hyperfine coupling constants the valuesa=(18.7±0.4) Mc/s andb=(3.4±0.4) Mc/s. The nuclear electric quadrupole moment derived from the ratio ofb/a isQ=(0.146±0.02) · 10^?24cm². The Lande factor and the lifetime for the 3²P_3/2state are g_J=1.3344±0.0004 and τ=(1.61±0.07) · 10^?8 sec.     

Bestimmung des elektrischen Kernquadrupolmomentes des ungeraden stabilen Strontium-87-Kerns

In order to determine the electric quadrupole moment of Sr⁸⁷ (I= 9/2) the hyperfine structure-splitting of the 5s5p ³ P ₁-state of the SrI-spectra was investigated by optical double resonance. By detection of high frequency transitions (ΔF=±1,Δm _F=0,±1) in an external magnetic fieldH ₀≈0 one obtains the hyperfine structure separations asv _F=11/2?F=9/2=1463·149 (6) Mc/sec andv _F=9/2?F=7/2=1130·264 (6) Mc/sec. From these frequencies one calculates the magnetic hyperfine structure-splitting constantA=?260·084 (2) Mc/sec and the electric quadrupole interaction constantB=?35·658 (6) Mc/sec. B leads to an electric quadrupole moment ofQ(Sr⁸⁷)=+0·36 (3)·10^?24 cm².     

Mode-crossing signals of high order on the 4d 95s 2 2 D 5/2 state of Cd II isotopes

In the linearly polarized radiation field of a 442 nm He-Cd laser containing a natural isotope mixture, saturation-induced mode-crossing signals of the 4d ⁹5s ^{2 2} _5/2 state of Cd II are observed due to the even as well as the odd isotopes. The signal width of about 10^?4 T yields high resolution. Thus the signal splitting respective to the magnetic quantum number can be resolved. Theg _J - andg _F -factors of the² D _5/2 state are determined as follows:g _J=1.1980±0.0036,g _F(F=2)=1.397±0.008,g _F(F=3)=1.002±0.009.     

Die Hyperfeinstruktur des angeregten 32P3/2-Zustandes von Natrium

The hyperfine structure of the 3²P_3/2-state in the Na(I)-spektrum was investigated by optical double resonance. Three zero fieldrf-transitions (ΔF=±1, Δm_F=0) were detected and thus the unambiguous interpretation of therf-spectrum was made possible. From an analysis of therf-spectrum one obtains the magnetic hyperfine structure splitting constant a=(18.5 _?0.2 ^+0.6 ) Mc/sec the electric quadrupole interaction constantb=(3.2±0.5) Mc/sec which yields an electric quadrupole moment Q(Na²³)=(0.138±0.025)·10²⁴cm².     

Experimentelle untersuchung der 5d6s6pz 2 F 5/2,7/2-Terme im Lanthan I-Spektrum unter Verwendung von Levelcrossing-Spektroskopie

The hyperfinestructure-interaction-constantsA/g _J andB/g _J of the 5d 6s6p z ² F _5/2,7/2 terms in the La I-spectrum were measured by levelcrossing technique. Using a La-atomic beam many levelcrossings between magnetic sublevels with ¦Δm¦=2 were detected in both terms by resonance scattering. Values for the lifetime of each state were deduced from the widths of Hanle-effect- and levelcrossing-signals.     

Untersuchung der Hyperfeinstruktur des 62 P 1/2-Zustandes von133Cs im starken Magnetfeld mit der optischen Doppelresonanzmethode

The hyperfine structure of the 6² P _1/2-state of¹³³Cs has been measured by optical double resonance in a strong magnetic field. From the positions of the magnetic dipole transitionsδm _J =±1,δm _I =0 theg _J -factorg _J(6² P _1/2)=0.66590(9) and the magnetic hfs-coupling constanta(6² P _1/2)=291.90(12) MHz could be derived.     

Nuclear reactions as an example of the quantum theory of irreversible processes

A modification of the atomic beam magnetic resonance method for investigation of the hyperfine structure of excited atomic states will be described. Radiofrequency transitions between the hyperfine structure niveaus of the excited state, which are unequally populated by circularly polarized light, are detected by observing the resulting change in population number of the hyperfine structure niveaus of the ground state using magnetic deflection in an inhomogeneous field and additional radiofrequency transitions in the ground state as analyzers. As an application the hyperfine structure of the excited 4² P _3/2-state of K³⁹ has been investigated in an almost strong magnetic field of about 65 G with a constant frequency of the applied radiofrequency field of 125.50 Mc/s. The analysis of the radiofrequency signal of the excited state detected as a change in the amplitude of a radiofrequency transition in the ground state yielded the valuesA=(6.10±0.25) Mc/s andB=(1.8±1.2) Mc/s for the hyperfine structure constants of the 4² P _3/2-state of K³⁹. Further possibilities for observing signals of the excited state with the apparatus used in this experiment are also discussed.     

Magnetic moment of the 5/2−1/2[541] ground state of 14h 185Ir

The magnetic and electric hyperfine splitting frequencies ¦gμ _N B _HF/h¦ ande ² qQ/h of the 5/2^?1/2[541] ground state of 14h ¹⁸⁵Ir in Ni were measured with nuclear magnetic resonance on oriented nuclei to be 360.8(7) MHz and +6.7(2.0) MHz, respectively. The ground state magnetic dipole moment and electric quadrupole moment of¹⁸⁵Ir are deduced to be ¦μ¦=2.601 (14)μ _N andQ=?1.9(5)b, taking values for the hyperfine field and electric field gradient of B_HF=?454.9 (2.3) kG and eq=?0.151(4) × 10¹⁷ V/cm², respectively. The negative quadrupole moment is in agreement with nuclear-orientation data and proves again theI ^π K=5/2^? 1/2 ground state configuration.     

Lebensdauer des 5s5p 3 P 1-Zustands von Strontium

The lifetime of the 5s5p ³ P ₁ state of Sr has been determined with optical double resonance by observation ofrf-transitionsΔm _J =±1 between Zeeman levels of the even isotopes. The measurement yields the value τ(5³ P ₁, Sr)=2.1(3) · 10^?5 sec. A new type of narrowing of optical double resonance signals due to a time-of-flight effect of the radiating atom has been observed and compared with the theory.     

Level-crossing-Experiment am 6s6p 3 P 1-Term im Ba I-Spektrum

The hfs-splitting of the stable odd Ba-isotopes Ba¹³⁵ and Ba¹³⁷ (I=3/2) in the 6s6p ³ P ₁-state was investigated by level crossing techniques. For both isotopes two crossings between Zeeman-sublevels withδm _F=2 were detected by resonance scattering of the 7911 å-intercombination line using a Ba-atomic beam. From the experimental results ratios of zero field hfs-constants and theg _J-value of the³ P ₁-state were calculated including second order corrections. The results may be compared with double resonance measurements in zero magnetic field.     

Hyperfine structure measurements in the4 I 9/2 ground state of141Pr

Using the atomic beam magnetic resonance method, the five hyperfine structure separations in the 4f ³ 6s ^{2 4}I_9/2 ground state of ₅₉ ¹⁴¹ Pr have been measured. The results are:F F′ E _FF′ ^* /h (MHz) 7 6 6477.913423(17) 6 5 5556.359848 (6) 5 4 4633.023306 (2) 4 3 3708.201146 (5) 3 2 2782.190601(15) From these quantities, the multipole interaction constantsA _k,k=1, 2, 3, 4 between the nucleus and the electron shell have been calculated.A ₄ especially then served to give the following limit for the intrinsic hexadecapole moment: ¦Q ₄₀¦<0.4eb ². Furthermore, theg _J -factors of the⁴ I multiplet have been measured at magnetic fields of 300 Oe. The results are:g _J(⁴ I _9/2)=0.7310371(15)g _J(⁴ I _11/2)=0.9651476(20)g _J(⁴ I _13/2)=1.1063197(40)g _J(⁴ I _15/2)=1.197963 (30) Small corrections due to perturbations by neighbouring fine structure levels are included.     

Level-crossing-Untersuchung der Hyperfeinstruktur des 3d 10 4p 2 P 3/2-Terms von Cu63 und Cu65

The level-crossing technic has been used to investigate the hyperfinestructur of the 3d ¹⁰ 4p ² P _3/2-term in Copper I by scattering the resonance line λ=3248 Å on an atomic beam of separated isotop Cu⁶³ respectively Cu⁶⁵ in an external magnetic field. From the level-crossing signals values for the magnetic dipol interaction constantsA and for the electric quadrupol interaction constantsB are deduced to beeA(Cu⁶³)=(194,72±0,15) Mc/secB(Cu⁶³)=?(28,8±0,6) Mc/secA(Cu⁶⁵)=(208,57±0,15) Mc/secB(Cu⁶⁵)=?(25,9±0,6) Mc/sec. With theA-value of the 3d ¹⁰ 4p²P_1/2-term from optical measurements the ratioA(² P _3/2)∶A(² P _1/2)≈0,4 is about twice greater than for an unperturbetalkali-like²P-term. From the width of the level-crossing signals a mean lifetime of the 3d¹⁰ 4p²P_3/2-term τ=(7,0±0,2) · 10^?9 sec is deduced.     

Mößbauereffekt in FeCl2, FeSO4 und FeSO4 · 7 H2O

Mößbauereffect measurements were performed with FeCl₂, FeSO₄ and FeSO₄ · 7 H₂O in the temperature range between 5 and 300 ?K. The quadrupole splittings at 5 ?K were determined to be (1.300±0.027) mm/sec, (3.650±0.053) mm/sec, and (3.350±0.053) mm/sec respectively. From the temperature dependence of the quadrupole splittings it follows that in FeCl₂ the energy of the excited 3d-electron-level isδ=150 cm^?1, in FeSO₄ δ ₁=360 cm^?1 andδ ₂=1680 cm^?1 and in FeSO₄ · 7 H₂Oδ ₁=480 cm^?1 andδ ₂=1300 cm^?1. The magnitudes of the magnetic field at the iron nucleus at 5 ?K are (202±8) kOe for FeSO₄ and (0±4) kOe for FeCl₂.     

Radiative lifetimes and tensor polarizabilities of 1s4f 1 F and 1s5f 1 F level of He I

He atoms have been excited by Ne⁺ ion impact and the depolarization of the fluorescence lines at 668 nm and 492 nm by magnetic and electric fields has been studied. The Ne⁺ ion energy could be chosen such that pure cascade level crossing signals were observed. From the widths of magnetic depolarization signals the radiative lifetimes τ(1s4f ¹ F)=74(2) ns and τ(1s5f ¹ F)=133(5) ns have been determined. By investigating the electric field splitting of the magnetic depolarization signals the tensor polarizabilities ¦α _ten(1s4f ¹ F)¦=0.58(1) kHz/(V/cm)² and ¦α _ten(1s5f ¹ F)¦=4.2(1) kHz/(V/cm)² have been deduced. From the latter value a mean frequencyv(1s5g?1s5f)=14.4 GHz of the transitions between the levels of the 1s5f configuration and those of the 1s5g configuration has been derived.α _ten(1s4f ¹ F) depends sensitively on the singlet-triplet mixing in the 1s4f configuration and thus a mixing coefficient could be deduced for this configuration.