The development of a simple device for the generation and control of radio frequency pulses, intended for experiments on pulsed electron nuclear double resonance (ENDOR), is presented. The device is implemented on a 32-bit microcontroller based on the Arm Cortex-M processor (STM32 family). The functionality of the device has been tested on an Elexsys E580 FT EPR spectrometer (Bruker, Germany) operating in the X and Q frequency bands. Within the limits of the developed device functionality it appeared to be compact and inexpensive, and comparable in performance to commercial devices

The point defects have been produced in the rutile structure by irradiation of a single crystalline (001)-TiO₂ rutile platet wih 40 keV Ar⁺ ions. It is found that Ar-ion bombardment of rutile results in a large number of positively charged oxygen vacancies and, as a consequence, leads to a change in the valence of neighbouring Ti cations. Electron paramagnetic resonance (EPR) of Ar-ion irradiated TiO₂ rutile is studied in detail. The analysis of angular and temperature dependences of EPR spectra makes it possible to conclude that EPR signals are associated with Ti³⁺ ions in the sixfold symmetric environment. In addition to the main signal from even titanium isotopes, eight equidistant weak lines are observed due to the hyperfine interaction typical for two titanium isotopes: ⁴⁷Ti with a nuclear spin I=5/2 (natural abundance of 7.4%) and ⁴⁹Ti with a nuclear spin I=7/2 (natural abundance of 5.4%). By comparing the g-tensor components with the reference data it is concluded that these Ti³⁺-based centers in Ar-ion implanted rutile were not described before.