27-10-2012, 03:15 PM
Wavelengths, f-Values, and Cross Sections in the UV Spectra of Astrophysical, Atoms, Ions, and Molecules
ABSTRACT
Data analysis for Fe III was completed in 2004. The new spectra give wavelengths and some energy levels for Fe III that
are at least an order of magnitude more accurate than values in the literature. However, the data set is missing - because they
are outside the wavelength range that we can study at Imperial College or with ancillary FT spectroscopy measurements at
NIST - important transitions that would allow all energy levels to be determined with improved accuracy. We are assessing
collaborations at other labs. We have made test runs with a number of cathodes (pure metals and alloys) in the Penning
discharge source and selected four iron group (3d) elements, Cr, Mn, Co, and Ni, for further measurements. Cathodes of pure
Cr and Co and an alloy of Ni were found to be best. Mn has not nm stably yet, and other cathode geometries or alloys may
need to be assessed. Optimum Penning discharge (PD) lamp conditions (buffer gas, gas pressure, and current/voltage) were
established for Co, and investigations are underway for Cr and Ni. Definitive measurements for Co await purchase of new
mirrors and photomultiplier tubes that will improve signal to noise ratio. Our plan for the next year is to continue evaluating
cathodes and operating conditions through March 05, and then to begin definitive measurements. The UV wavelength
measurements made at Imperial College with the unique UV FT spectrometer will be complemented by visible and near IR
range measurements at NIST in June and/or July. Approximately one year from now, we intend to visit Lund University to
collaborate on lifetime measurements that will allow our branching ration data to be used to determine f-values.
ABSTRACT
Data analysis for Fe III was completed in 2004. The new spectra give wavelengths and some energy levels for Fe III that
are at least an order of magnitude more accurate than values in the literature. However, the data set is missing - because they
are outside the wavelength range that we can study at Imperial College or with ancillary FT spectroscopy measurements at
NIST - important transitions that would allow all energy levels to be determined with improved accuracy. We are assessing
collaborations at other labs. We have made test runs with a number of cathodes (pure metals and alloys) in the Penning
discharge source and selected four iron group (3d) elements, Cr, Mn, Co, and Ni, for further measurements. Cathodes of pure
Cr and Co and an alloy of Ni were found to be best. Mn has not nm stably yet, and other cathode geometries or alloys may
need to be assessed. Optimum Penning discharge (PD) lamp conditions (buffer gas, gas pressure, and current/voltage) were
established for Co, and investigations are underway for Cr and Ni. Definitive measurements for Co await purchase of new
mirrors and photomultiplier tubes that will improve signal to noise ratio. Our plan for the next year is to continue evaluating
cathodes and operating conditions through March 05, and then to begin definitive measurements. The UV wavelength
measurements made at Imperial College with the unique UV FT spectrometer will be complemented by visible and near IR
range measurements at NIST in June and/or July. Approximately one year from now, we intend to visit Lund University to
collaborate on lifetime measurements that will allow our branching ration data to be used to determine f-values.