Electrical detection of Rydberg interactions in nitric oxide at room temperature

In this work I will present measurements of Rydberg states in nitric oxide (NO) at room temperature. The detection of the Rydberg states is realized by measuring the current of free charges resulting from collisions of the excited molecules. All measurements are performed using continuous-wave (cw) lasers in a sub-Doppler configuration, which together with a stabilization setup yield a frequency error of only 2 × 2.5 MHz. The full width at half maximum (FWHM) of a typical Rydberg state is only about 2 × 130 MHz. We take a look at the necessary theory of diatomic molecules first. Afterward, a thorough walkthrough of the experimental setup is given. The heart of our setup is a custom-designed measurement cell, which features readout electronics based on a transimpedance amplifier (TIA). As such I will also give an overview on the basics of operational amplifiers (OpAmps). When all prerequisites are introduced, we will take an in-depth look on the Stark effect in Rydberg states. To our knowledge, the presented resolution is unmatched, and may enable us to give a more precise value to the g–quantum defect in NO in the future. In a final experimental section I show the collisional broadening and shift of Rydberg states of NO due to an increasing background gas density. Such measurements have a long history in alkalis, yet to our knowledge, no such measurements in NO exist. The overall experiment is performed in the context of a trace-gas sensor for NO in a medical application. This work gives suitable density and electric field ranges for such a sensor

Doppler-free high resolution continuous wave optical UV-spectroscopy on the \mathrm{A}\,^2\Sigma^+ \leftarrow \mathrm{X}\,^2\Pi_{3/2} transition in nitric oxide

We report on Doppler-free continuous-wave optical UV-spectroscopy resolving the hyperfine structure of the \mathrm{A}\,^2\Sigma^+ \leftarrow \mathrm{X}\,^2\Pi_{3/2} transition in nitric oxide for total angular momenta $J_X=1.5-19.5$ on the $\mathrm{oP_{12ee}}$ branch. The resulting line splittings are compared to calculated splittings and fitted determining new values for the molecular constants $b, c, eQq_0$ and $b_F$ for the \mathrm{A}\,^2\Sigma^+ state. The constants are in good agreement with values previously determined by quantum beat spectroscopy.Comment: 8 Pages, 4 figure

Ultraviolet photodetectors and readout based on a‐IGZO semiconductor technology

In this work, real-time ultraviolet photodetectors are realized through metal–semiconductor–metal (MSM) structures. Amorphous indium gallium zinc oxide (a-IGZO) is used as semiconductor material and gold as metal electrodes. The readout of an individual sensor is implemented by a transimpedance amplifier (TIA) consisting of an all-enhancement a-IGZO thin-film transistor (TFT) operational amplifier and a switched capacitor (SC) as feedback resistance. The photosensor and the transimpedance amplifier are both manufactured on glass substrates. The measured photosensor possesses a high responsivity R, a low response time tRES, and a good noise equivalent power value NEP.Deutsche ForschungsgemeinschaftProjekt DEA

Collisional shift and broadening of Rydberg states in nitric oxide at room temperature

We report on the collisional shift and line broadening of Rydberg states in nitric oxide (NO) with increasing density of a background gas at room temperature. As a background gas we either use NO itself or nitrogen (N$_{2}$). The precision spectroscopy is performed by a sub-Doppler three-photon excitation scheme with a subsequent readout of the Rydberg states realized by the amplification of a current generated by free charges due to collisions. The shift shows a dependence on the rotational quantum state of the ionic core and no dependence on the principle quantum number of the orbiting Rydberg electron. The experiment was performed in the context of developing a trace-gas sensor for breath-gas analysis in a medical application