Preparation of circular Rydberg states in helium using the crossed fields method

Helium atoms have been prepared in the circular $|n=55,\ell=54,m_{\ell}=+54\rangle$ Rydberg state using the crossed electric and magnetic fields method. The atoms, initially travelling in pulsed supersonic beams, were photoexcited from the metastable 1s2s\,^3S_1 level to the outermost, $m_{\ell}=0$ Rydberg-Stark state with $n=55$ in the presence of a strong electric field and weak perpendicular magnetic field. Following excitation, the electric field was adiabatically switched off causing the atoms to evolve into the circular state with $m_{\ell}=+54$ defined with respect to the magnetic field quantization axis. The circular states were detected by ramped electric field ionization along the magnetic field axis. The dependence of the circular state production efficiency on the strength of the excitation electric field, and the electric-field switch-off time was studied, and microwave spectroscopy of the circular-to-circular $|55,54,+54\rangle\rightarrow|56,55,+55\rangle$ transition at $\sim38.5$~GHz was performed.Comment: 10 pages, 8 figure

Electrically tuned Forster resonances in collisions of NH3 with Rydberg He atoms

The effects of weak electric fields on resonant energy transfer between NH3 in the X 1 A1 ground electronic state and Rydberg He atoms in triplet states with principal quantum numbers n = 36–41 have been studied in a crossed-beam apparatus. For these values of n, electric dipole transitions between the Rydberg states that evolve adiabatically to the |ns and |np states in zero electric field can be tuned into resonance with the ground-state inversion transitions in NH3 using electric fields, with energy transfer occurring via Förster resonance. In the experiments the Rydberg He atoms, traveling in pulsed supersonic beams, were prepared by resonant two-photon excitation from the metastable 1s2s 3 S1 level and crossed an effusive beam of NH3 before being detected by state-selective pulsed-electric-field ionization. The resonant-energy-transfer process was identified by monitoring changes in the ionization signal from the |ns and |np Rydberg states for each value of n. The electric-field dependence of the experimental data is in good agreement with the results of calculations in which the resonant dipole-dipole coupling between the collision partners was accounted for.

Mean-field energy-level shifts and dielectric properties of strongly polarized Rydberg gases

Mean-field energy-level shifts arising as a result of strong electrostatic dipole interactions within dilute gases of polarized helium Rydberg atoms have been probed by microwave spectroscopy. The Rydberg states studied had principal quantum numbers n=70 and 72, and electric dipole moments of up to 14 050 D, and were prepared in pulsed supersonic beams at particle number densities on the order of 108 cm−3. Comparisons of the experimental data with the results of Monte Carlo calculations highlight effects of the distribution of nearest-neighbor spacings in the pulsed supersonic beams, and the dielectric properties of the strongly polarized Rydberg gases, on the microwave spectra. These observations reflect the emergence of macroscopic electrical properties of the atomic samples when strongly polarized

Preparation of circular Rydberg states in helium with n ≥ 70 using a modified version of the crossed-fields method

Circular Rydberg states with n = 70 have been prepared in helium using a modified version of the crossed-fields method. This approach to the preparation of high-n circular Rydberg states overcomes limitations of the standard crossed-fields method which arise at this, and higher, values of n. The experiments were performed with atoms traveling in pulsed supersonic beams that were initially laser photoexcited from the metastable 1s2s³S₁ level to the 1s73s³S₁ level by resonance-enhanced two-color two-photon excitation in a magnetic field of 16.154 G. These excited atoms were then polarized using a perpendicular electric field of 0.844 V/cm, and transferred by a pulse of microwave radiation to the state that, when adiabatically depolarized, evolves into the n = 70 circular state in zero electric field. The excited atoms were detected by state-selective electric field ionization. Each step of the circular state preparation process was validated by comparison with the calculated atomic energy-level structure in the perpendicular electric and magnetic fields used. Of the atoms initially excited to the 1s73s³S₁ level, ∼ 80% were transferred to the n = 70 circular state. At these high values of n, Δn = 1circular-to-circular Rydberg state transitions occur at frequencies below 20 GHz. Consequently, atoms in these states, and the circular state preparation process presented here, are well suited to hybrid cavity QED experiments with Rydberg atoms and superconducting microwave circuits

PHARMACOGENETIC STUDY OF THE ACETYLATION PHENOTYPE IN A BULGARIAN POPULATION

N-acetyltransferase, an enzyme involved in the metabolic inactivation of drugs like isoniazide, some sulfonamides and others is well-known to he under polymorphic genetic control. The acetylation phenotype of the patients may serve as an important guide in foretelling the therapeutic efficacy or tolerahility of a particular drug. In the present study we investigated the distribution of the acetylaiion phenotypes in a group of 100 healthy volunteers of both sexes using sulfadimidine as a substrate. The distribution was found to follow a bimodal pattern, as aspected, with a slight predominance of the "slow" acetylators - in 58 % of the cases, a finding similar to literature data from neighbouring and other European countries. In the men's group the distribution was approximately the same as that in the whole group whilst in the women's one the "rapid" inactivators prevailed. This work represents the first modest attempt in Bulgaria for phenotyping the population according to the individual acetylaiion status