The low-lying structures of the extremely neutron-deficient nuclei ¹⁰⁶Te, ¹⁰⁷Te, ¹¹⁰Xe, ¹⁷⁰Ir and ¹⁷²Au have been investigated experimentally. Prompt gamma rays emitted in fusion-evaporation reactions were detected by the Jurogam HPGe array. The gamma rays were assigned to specific reaction channels using the recoil-decay tagging technique provided by the gas-filled separator RITU and the GREAT focal-plane spectrometer. The experimental set-up and the technique used to extract the information from the experimental data are described in detail.

Results were interpreted in terms of the nuclear shell model and Total Routhian Surface calculations. In addition, decay studies on ¹⁷⁰Ir, ¹⁷²Au and ¹⁶⁴Re led to the discovery of new alpha-decay branches in these nuclei.

Atomic nuclei are complex many-body systems and exhibit an interplay between single-particle and collective degrees of freedom. In order to describe and predict the “behavior” of nucleons inside the nuclei a variety of theoretical models have been created, each applicable to their own domain of nuclear phenomena. Experimental information is needed in order to test and improve the various theoretical models with the ultimate goal of creating unified theory of nuclear structure. In-beam γ-ray spectroscopy is one way of probing the inner structure of nuclei and it is the subject of this thesis, which describes the first identification of excited states in the extremely neutron deficient nuclei ¹⁰⁶Te and ¹⁰⁷Te. The experiments were performed at the Accelerator Laboratory of the University of Jyväskylä, Finland, using the recoil-decay tagging technique. Prompt γ rays emitted following fusion evaporation reactions were detected by the Jurogam detector array and the selection of the γ rays of interest was based on the recoil identification provided by the RITU gas-filled recoil separator and the GREAT focal plane spectrometer. The production cross sections were estimated to be 25nb and 1μb for ¹⁰⁶Te and ¹⁰⁷Te, respectively. In case of the nucleus ¹⁰⁶Te, several γ rays have been observed. A vibrational-like yrast band has been suggested. For ¹⁰⁷Te a number of γ rays have been assigned and a tentative partial level scheme has been suggested. The experimental data have been compared to shell model calculations.