High‐temperature, high‐resolution photoabsorption cross sections of O₂ in the 108.5‐nm region

Measurements of rovibronic line oscillator strengths of N2 in the 83.4 nm region: A high‐resolution high‐temperature study

“…The experimental arrangement employed in the present work has been previously described in detail [ Wu et al , 2000]. Briefly, it consists of an intense light source, a high‐temperature windowless absorption cell, an ultrahigh‐resolution spectrometer, and a data acquisition system.…”

“…Briefly, it consists of an intense light source, a high‐temperature windowless absorption cell, an ultrahigh‐resolution spectrometer, and a data acquisition system. The windowless high‐temperature (300 to 900 K) absorption cells with a path length of 16.24 cm [ Wu et al , 1998] and 11.7 cm [ Wu et al , 2005, 2000] and with two 1.0 mm diameter apertures were used in the absorption cross‐section measurements. This windowless, high‐temperature cell is a unique facility and is the only one in the world that is currently in operation associated with high‐resolution cross‐section studies.…”

“…The reciprocal linear dispersion is 0.02 nm/mm in the sixth order, which gives a resolving power of 3 × 10 5 in the 83.4 nm spectral region. The resolution of the 6‐VOPE facility is 3 × 10 −4 nm in the photographic mode and 6 × 10 −4 nm in the photoelectric mode using a stepping speed of 1.4 × 10 −4 nm/step [ Wu et al , 2005, 2000] and 7 × 10 −5 nm/step [ Wu et al , 1998]. The photoelectric mode was employed in the present work.…”

“…Using a similar pumping speed at the Photon Factory 6VOPE facility, the calibration was done by making use of the well known absorption cross section of the Schumann‐Runge continuum of O 2 in the 140 nm region [ Gibson et al , 1983]. The systematic errors in the cross section determination [ Wu et al , 2000] can be as large as 10% due to uncertainties in the gas pressure, light intensities, and the published cross‐section values of the S‐R continuum. The wavelength calibration was carried out using the known reported spectral positions of N 2 [ Carroll and Yoshino , 1972; Carroll et al , 1970] as the standard, which have an accuracy of 3.5 × 10 −4 nm to 6 × 10 −4 nm.…”

“…Therefore in the present work we report measurements of the integrated oscillator strength ( f ‐value) for each rovibronic line. We have previously carried out similar measurements in the O 2 molecule but with a lower resolution [ Wu et al , 2005, 2001, 2000].…”