Radiativelifetimesforthelevelsofthe3s 2 3p 2 4pcon- figuration in neutral phosphorus have been determined experi- mentally for the first time and also theoretically. Experiments were performed by using two-photon UV laser excitation and subsequent fluorescence detection in a laser-produced plasma. In relativistic Hartree-Fock calculations, the Cowan code ex- tended to 42 configurations was used. Finally, the lifetimes for all the 13 excited states in the 4p configuration were calculated and for 6 of them the values were measured experimentally. Theoretical branching ratios were combined with experimental lifetimes, to deduce oscillator strengths and these were used for the evaluation of the phosphorus abundance in the sun. A value of 5.49 (0.04) was obtained in the usual logarithmic scale.
Photodynamic therapy (PDT) using topical application of the Protoporphyrin IX (PpIX) precursor (delta) -amino levulinic acid (ALA) in various malignant skin tumors is a new promising treatment modality. We have treated an extensive number of non-melanoma malignancies of the skin over the past three years with very satisfying initial results. For superficial, shallow lesions one treatment session is sufficient. In thicker lesions, such as nodular basal cell carcinomas, complete treatment response is achieved after two or three treatment sessions. In conjunction with the treatment procedure the tissue fluorescence and the superficial blood flow have been investigated during and after the treatment procedures. The PpIX build-up has been detected in vivo and the degree of tumor selectivity has been evaluated using laser-induced fluorescence. Also changes in the bloodflow in tumors compared to normal skin before, during, and after the treatment procedure has been followed using a laser- Doppler perfusion imaging system. Results from the measurements in basal cell carcinomas (BCCs), Mb. Bowen lesions (squamous cell carcinoma in situ) and cutaneous T-cell lymphoma lesions are presented.
Osteonecrosis of the femoral head is caused by inadequate blood supply to the affected bone. The bone decay process due to lacking blood supply would be likely to be accompanied by the formation of gas-filled pores. We have introduced diode laser absorption spectroscopy to successfully detect water vapor signals from pores in the femoral heads retrieved from hip replacement operations in 19 patients. The Gas in Scattering Media Absorption Spectroscopy (GASMAS) variety of tunable laser spectroscopy was employed. The results open up for the possibility of improved diagnostics for a very common disease.
Splittings in the n2D sequence were measured for n=4-9. An accuracy of about 0.1% was obtained in level-crossing measurements on an atomic beam. The D states were populated by step-wise excitation, using an RF lamp and a CW dye laser. A method for measuring the sign of the spin-orbit coupling constant is demonstrated. With the present measurements, the highly anomalous n2D sequence in sodium has now been studied for n=3-16.
Experiments for measuring gas diffusion through porous alumina ceramics are described. With the gas in scattering media absorption spectroscopy (GASMAS) technique, gaseous oxygen signals are measured continuously during the gas diffusion process. It is experimentally demonstrated that the time-dependence of the transient oxygen signal is described by an exponential curve. Moreover, the effect on gas diffusion of material porosity and whether water is present or not is also experimentally investigated.
Optical spectroscopy is becoming a very valuable diagnostic tool in biomedical research. Time-of-flight spectroscopy is a tool providing information regarding scattering and absorption properties of the tissue. A unique broadband time-resolved spectroscopy system for turbid media, consists of a mode-locked Ti:sapphire laser pumping a photonic crystal fibre (PCF) and a streak-camera in syncroscan mode. This system is based on the technique called time-correlated single photon counting (TCSPC). This equipment is designed to allow in vivo measurement of tissue optical properties of small tissue volumes.
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