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 Title: PROBING THE ZEEMAN EFFECT IN LOW-Ω F4∆← X 4∆ TRANSITIONS IN FeH Author(s): Ross, Amanda J. Contributor(s): Adam, Allan G.; Crozet, Patrick Subject(s): Astronomy Abstract: This work targets laboratory studies of the Zeeman effects in selected transitions of the FeH radical, observed in the atmospheres of dwarf stars. The \emph{F}$\leftarrow$\emph{X} electronic system falls around 1 $\mu$m, and matches observation windows of the high-resolution spectropolarimeters SPIRou (brought into service in 2019) and ESPaDOnS mounted at the Canada-France-Hawaii Telescope. Many field-free line positions have already been reported for this radical from laboratory studies, notably from high-temperature sources\footnote{Line intensities and molecular opacities of the FeH $\emph{F}^4\Delta_{i}\leftarrow \emph{X}~^4\Delta_i$ transition; Dulick $et~al$; Astrophys. J., \underline{594}, 651-63, (2003)}\footnote{The near-Infrared Spectrum of the FeH Molecule; Phillips $et~al$; Astrophys. J. Supp. Ser., 65, 721-78, (1987)}. Our earlier work with a sputter source\footnote{Determination of Land\'e factors in the $F~^4\Delta_{\frac{5}{2},\frac{7}{2}}$ state of FeH by laser excitation spectroscopy; Crozet $et~al.$; J. Mol. Spectrosc., \underline{303}, 46-53, (2014)} yielded information on magnetic response for just a few transitions between the two lowest spin components of the $F$ and $X$ states. We report here some preliminary results obtained from FeH formed in reaction between hydrogen atoms (generated in a microwave discharge of H$_2$ in argon) and traces of iron pentacarbonyl vapour, at pressures around 1 Torr. This source\footnote{Detection of the free radicals FeH, CoH and NiH by far IR laser magnetic resonance; Beaton $et~al.$; J. Chem. Phys. \underline{89}, 4446-48, (1988)} seems to produce more population in the $\emph{X}~^4\Delta_{3/2}$ and $\emph{X}~^4\Delta_{1/2}$ components of the ground state. Laser excitation of [1-0] transitions, with lock-in detection of fluorescence in the [1-1] band to eliminate laser scatter, has allowed some Zeeman-broadened profiles to be measured. Issue Date: 23-Jun-20 Publisher: International Symposium on Molecular Spectroscopy Citation Info: APS Genre: CONFERENCE PAPER/PRESENTATION Type: Text Language: English URI: http://hdl.handle.net/2142/107379 Date Available in IDEALS: 2020-06-26
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