We have investigated electromagnetically induced transparency in the spectrum of selective reflection at the interface of Rb atom vapors and a dielectric nanocell window. A nanocell with atomic vapor column thicknesses ranging from 150 to 1200 nm, as well as a 50~
μm thickness microcell were used. We have compared electromagnetically induced transparency observed for the cases of the selective reflection and transmission. It was demonstrated that for the thicknesses of below
≤1000 nm selective reflection technique is more favorable. In contrast, for wider cells and microcells, using transmitted radiation as probe field is more effective.
We report on rubidium vapor-cell Rydberg electromagnetically induced transparency (EIT) in a 0.7~T magnetic field where all involved levels are in the hyperfine Paschen-Back regime, and the Rydberg state exhibits a strong diamagnetic interaction with the magnetic field. Signals from both
85Rb and
87Rb are present in the EIT spectra. This feature of isotope-mixed Rb cells allows us to measure the field strength to within a
±0.12\% relative uncertainty. The measured spectra are in excellent agreement with the results of a Monte Carlo calculation and indicate unexpectedly large Rydberg-level dephasing rates. Line shifts and broadenings due to small inhomogeneities of the magnetic field are included in the model.