<p>This thesis is based on a selection of six different experimental techniques used for studies in atomic and molecular physics. The techniques analysed in the thesis are compared to find similarities in strategies and ways to avoid sources of error.</p><p>Paper 1 deals with collision based spectroscopy with 60 keV Xe6+ ions on sodium and argon gas targets. Information on energy of Rydberg states in Xe5+ is unveiled by optical spectroscopy in the wavelength range from vacuum ultraviolet (VUV) to visible. In paper 2, the fast ion-beam laser spectroscopy (FIBLAS) is adapted for measuring hyperfine structure of barium isotopes in an isotopically pure ion-beam. This techniques involves changing the isotope during the measurement to minimize sources of error in measurement and enhance the signal from lesser abundant isotopes. The FIBLAS technique is used in paper 3 to study samarium ions. The ions are optically pumped and the recorded optical nutation is used to measure transition probabilities. This technique eludes the difficulties inherent in relative intensity measurements of all the radiative transitions from an excited state. In Paper 4, optical emission spectroscopy is used in the VUV region to study noble gas mixture discharges. The source of the emission bands near the resonance lines of krypton and xenon are found to be heteronuclear dimers. In paper 5, radiation from a pulsed argon plasma with admixture of nitrogen is studied with time resolved spectroscopy in the VUV and ultraviolet wavelength ranges to investigate the mechanism of energy transport. A metastable state of atomic argon is found to be an important source of energy to many radiative processes. In Paper 6, photoelectron spectroscopy (PES) on thiophene, on 3-bromothiophene and on 3,4-dibromothiophene using time-of-flight photoelectron-photoelectron coincidence technique and conventional PES to investigate the onset of double ionisation compared to the onset of single ionisation in molecules.</p>

This thesis is based on a selection of six different experimental techniques used for studies in atomic and molecular physics. The techniques analysed in the thesis are compared to find similarities in strategies and ways to avoid sources of error. Paper 1 deals with collision based spectroscopy with 60 keV Xe6+ ions on sodium and argon gas targets. Information on energy of Rydberg states in Xe5+ is unveiled by optical spectroscopy in the wavelength range from vacuum ultraviolet (VUV) to visible. In paper 2, the fast ion-beam laser spectroscopy (FIBLAS) is adapted for measuring hyperfine structure of barium isotopes in an isotopically pure ion-beam. This techniques involves changing the isotope during the measurement to minimize sources of error in measurement and enhance the signal from lesser abundant isotopes. The FIBLAS technique is used in paper 3 to study samarium ions. The ions are optically pumped and the recorded optical nutation is used to measure transition probabilities. This technique eludes the difficulties inherent in relative intensity measurements of all the radiative transitions from an excited state. In Paper 4, optical emission spectroscopy is used in the VUV region to study noble gas mixture discharges. The source of the emission bands near the resonance lines of krypton and xenon are found to be heteronuclear dimers. In paper 5, radiation from a pulsed argon plasma with admixture of nitrogen is studied with time resolved spectroscopy in the VUV and ultraviolet wavelength ranges to investigate the mechanism of energy transport. A metastable state of atomic argon is found to be an important source of energy to many radiative processes. In Paper 6, photoelectron spectroscopy (PES) on thiophene, on 3-bromothiophene and on 3,4-dibromothiophene using time-of-flight photoelectron-photoelectron coincidence technique and conventional PES to investigate the onset of double ionisation compared to the onset of single ionisation in molecules.