The LARISSA group develops multi-step resonance ionization laser spectroscopy and RIMS: element- and isotope-selective laser ionization used both as an ultratrace analytical technique (actinide detection at extreme selectivity, environmental and nuclear-forensic samples) and as a spectroscopy tool for exotic and short-lived isotopes, feeding ion-source development for facilities such as ISOLDE/CERN. A major current thrust is the atomic and ionic spectroscopy of thorium, including the 229mTh isomer that underpins the nuclear-clock effort, done jointly with Schmidt-Kaler's trap group and Duellmann's nuclear chemistry. Relative to the established NV-ensemble quantum-sensing playbook (DEER, nanoscale NMR, T1 relaxometry at pT/sqrt(Hz) ensemble sensitivity), the transferable capability here is selective, quantum-state-resolved detection of single atoms/ions -- the readout problem, approached spectroscopically rather than magnetically.