The influence of the interaction of Cs atoms with a dielectric surface on the position and shape of the hyperfine components of the D2 line at nanometer-order distances between atoms and the surface is studied. The use of a nanocell with a wedge-shaped gap made it possible to study the dependence of the shifts of all the hyperfine components of the D2 line corresponding to the transitions Fg = 3- Fe = 2, 3, 4 and Fg = 4- Fe = 3, 4, 5, on the distance L between the atoms and the sapphire surface windows in the range of 50–400 nm. At L less than 100 nm, due to the van der Waals interaction, there is a strong broadening of atomic transitions and a shift of their frequencies to the low-frequency region of the spectrum (red shift). The calculation of the second derivative (SD) of the vapor absorption spectra in the nanocell allows one to spectrally resolve the hyperfine components of the atomic transition down to L about 50 nm and measure the coefficient of the van der Waals interaction C3. It is shown that, at L <100 nm, an additional red shift occurs with increasing atomic density, while at relatively large distances between atoms and the surface L about 400 nm, an increase in atomic density causes a blue shift of the atomic transition frequencies. The above results are important in the development of miniature submicron devices containing atomic vapor of alkali metal.
A nanocell filled with atomic vapors of rubidium and potassium was used to develop a modified method of Faraday rotation. The formed lines are characterized by a spectral width that is a factor of 1.5‒2 smaller than those obtained by traditional method of Faraday rotation in nanocells. The new method allows obtaining the spectral width of atomic line that is 8 times smaller than the Doppler broadening in the case of the D _2 line of rubidium and 15 time smaller than the Doppler broadening in the case of the D _1,2 lines of potassium. In magnetic fields B = 100−1200 G, all atomic lines of Rb and K atoms are spectrally resolved and identified. In the case of the D _2 line of Rb, it is demonstrated that the probabilities of magneto-induced transitions (^87Rb, F _ g = 1 → F _ e = 3 and ^85Rb, F _ g = 2 → F _ e = 4) can exceed the probabilities of the allowed transitions. Convenience and efficiency of the modified method of Faraday rotation for high-resolution spectroscopy is demonstrated.
Для измерения коэффициентов уширения и сдвига линий D1 и D2 атомов Rb неоном использована ячейка субмикронной толщины. Разрешение сверхтонких компонент достигнуто комбинацией двух приемов. Во-первых, толщина столба паров Rb в направлении распространения лазерного излучения выбиралось равной половине его длины волны λ в условиях резонанса с частотой атомного перехода. Для атомов рубидия λ/2~400 nm. При толщине наноячейки L~λ/2 в спектре пропускания A(ν) происходит сужение спектральных линий атомных переходов за счет исключения доплеровского уширения. Во-вторых, дальнейшее сужение регистрируемых сигналов достигалось путем двойного дифференцирования спектра пропускания A''(ν). Измерены спектры пропускания чистых паров рубидия и паров рубидия с добавкой неона при различных давлениях. Измеренные величины коэффициентов сдвига линий D1 и D2 рубидия в присутствии Ne составили -1.1±0.2 MHz/Torr и -2.1±0.2 MHz/Torr соответственно. Коэффициенты уширения линий D1 и D2 совпадают и составляют 10±1 MHz/Torr. Благодаря высокому спектральному разрешению методика позволяет проводить измерения для каждого индивидуального перехода в отдельности. Ключевые слова: рубидий, неон, щелочные металлы, благородные газы, уширение спектральных линий, наноячейка, бездоплеровская спектроскопия, столкновительное уширение, буферные газы.
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