The hyperfine structures of the
82S21 and
92S21 states of
87Rb and of the
122S21 state of
133Cs have been measured by the method of stepwise excitation spectroscopy using a cw dye laser. We measure the magnetic dipole coupling constants to be $A(8^{2}S_{\frac{1}{2}}, ^{87}\mathrm{Rb})=159.2\ifmmode\pm\else\textpm\fi{}1.5$ MHz, $A(9^{2}S_{\frac{1}{2}}, ^{87}\mathrm{Rb})=90.9\ifmmode\pm\else\textpm\fi{}0.8$ MHz, and $A(12^{2}S_{\frac{1}{2}}, ^{133}\mathrm{Cs})=26.31\ifmmode\pm\else\textpm\fi{}0.10$ MHz.
We have measured the hyperfine structure in many highly-excited
S and
P states of
87Rb and
133Cs. The results for the magnetic-dipole coupling constants are, in MHz, for
87Rb:
A(102S21)=56.3(2),
A(112S21)=37.4(3); and for
133Cs:
A(92S21)=110.1(5),
A(132S21)=18.4(1),
A(142S21)=13.4(1),
A(152S21)=10.1(1),
A(162S21)=7.73(5),
A(172S21)=6.06(10),
A(102P21)=13.9(2).
We report the first successful measurements by cascade radio-frequency spectroscopy of the hyperfine structures of excited
S and
D states of rubidium. We obtain the following magnetic dipole coupling constants (in MHz): for
Rb87, $A(7^{2}S_{\frac{1}{2}})=312.5\ifmmode\pm\else\textpm\fi{}3.5$, $A(5^{2}D_{\frac{3}{2}})=14.1\ifmmode\pm\else\textpm\fi{}0.5$, $A(5^{2}D_{\frac{5}{2}})=\ensuremath{-}8.0\ifmmode\pm\else\textpm\fi{}1.5$; for
Rb85, $A(7^{2}S_{\frac{1}{2}})=92.6\ifmmode\pm\else\textpm\fi{}1.0$, $A(5^{2}D_{\frac{3}{2}})=4.1\ifmmode\pm\else\textpm\fi{}0.5$. The anomalous, negative value of
A for the
52D25 state may be related to the anomalously small fine-structure interval of the
5D state of rubidium.
We present measurements of the hyperfine structure (HFS) of the
nPJ Rydberg states for a large range of principal quantum number
n (n=41−−55) employing microwave spectroscopy in an ultracold cesium Rydberg ensemble. A microwave field with $30\text{\ensuremath{-}}\textmu{}\mathrm{s}$ duration couples the $nS\ensuremath{\rightarrow}nP$ transition, yielding a narrow linewidth spectroscopy that approaches the Fourier limit, which allows us to resolve the hyperfine structure of
nPJ states. By analyzing the hyperfine splittings of
nPJ states, we determine the magnetic dipole HFS coupling constant
AHFS,P1/2=3.760(26) GHz for the
P1/2 state, and
AHFS,P3/2=0.718(27) GHz and ${\overline{B}}_{\mathrm{HFS},{P}_{3/2}}=\ensuremath{-}0.084(102)$ GHz for the
P3/2 state. Systematic uncertainties caused by stray electromagnetic field, microwave field power, and Rydberg interaction are analyzed. This measurement is significant for the investigation of Rydberg electrometry and quantum simulation with dipole interaction involving the
nPJ state.
The hyperfine structure of the second-excited
D states of
85Rb,
85Rb, and
133Cs has been measured by the method of cascade-radio-frequency spectroscopy and cascade-level crossing. The sign of the magnetic-dipole coupling constant
A is determined by the method of cascade-decoupling and cascade-radio-frequency spectroscopy with narrow-band excitation. Lifetimes $\ensuremath{\tau}$ of some of these states are measured by the cascade-Hanle effect. We find that for
87Rb, $A(5^{2}D_{\frac{3}{2}})=14.43\ifmmode\pm\else\textpm\fi{}0.23$ MHz, $A(5^{2}D_{\frac{5}{2}})=\ensuremath{-}7.44\ifmmode\pm\else\textpm\fi{}0.10$ MHz, $\ensuremath{\tau}(5^{2}D_{\frac{3}{2}})=205\ifmmode\pm\else\textpm\fi{}40$ nsec; for
85Rb, $A(5^{2}D_{\frac{3}{2}})=4.18\ifmmode\pm\else\textpm\fi{}0.20$ MHz, $A(5^{2}D_{\frac{5}{2}})=\ensuremath{-}2.12\ifmmode\pm\else\textpm\fi{}0.20$ MHz; for
133Cs, $A(6^{2}D_{\frac{3}{2}})=16.30\ifmmode\pm\else\textpm\fi{}0.15$ MHz, $A(6^{2}D_{\frac{5}{2}})=\ensuremath{-}3.6\ifmmode\pm\else\textpm\fi{}1.0$ MHz, $\ensuremath{\tau}(6^{2}D_{\frac{3}{2}})=57\ifmmode\pm\else\textpm\fi{}15$ nsec.
We measure the hyperfine structure of
nP1/2 Rydberg states for
n= 42, 43, 44, and 46 using mm-wave spectroscopy on an ensemble of laser-cooled
85Rb atoms. Systematic uncertainties in our measurement from the Zeeman splittings induced by stray magnetic fields and dipole-dipole interactions between two Rydberg atoms are factored in with the obtained statistical uncertainty. Our final measurement of the
nP1/2 hyperfine coupling constant is
AHFS=1.443(31) GHz. This measurement is useful for studies of long-range Rydberg molecules, Rydberg electrometry, and quantum simulation with dipole-dipole interactions involving
nP1/2 atoms.