Line positions and line strengths for the 3← electric quadrupole band of H2Σg+1

Abstract

Several rotational lines in the S and Q branches [including the previously unobserved Q(2) and Q(3) lines] of the 3-0 electric quadrupole band of H2 have been detected by cavity ring-down spectroscopy. Line strengths were measured at densities between 2.7x10(18) and 7.5x10(19) molecules cm-3 at room temperature. The observed line strengths in the S branch are consistent with earlier measurements, and systematically below theoretical calculations [relative differences of approximately 10% for the S(1),S(2), and S(3) lines, and nearly 30% for the S(0) line]. Line strength measurements for the Q branch range from 25% to 33% below theoretical calculations.

THEv= 3 ← 0S(0)-S(3) ELECTRIC QUADRUPOLE TRANSITIONS OF H2NEAR 0.8 μm

“…But applications are limited by the uncertainties in the observed quadrupole transition probabilities. The measured (1-0) and (2-0) band transition intensities (Bragg et al 1982) agree well with the calculated results (Wolniewicz et al 1998;Campargue et al 2012), but higher overtones (Bragg et al 1982;Ferguson et al 1993;Robie & Hodges 2006) show systematic deviations. In particular, a discrepancy up to 30% has been reported for the intensities of the (3-0) band transitions detected by a pulsed cavity ring-down (CRD) spectrometer (Robie & Hodges 2006).…”

“…The measured (1-0) and (2-0) band transition intensities (Bragg et al 1982) agree well with the calculated results (Wolniewicz et al 1998;Campargue et al 2012), but higher overtones (Bragg et al 1982;Ferguson et al 1993;Robie & Hodges 2006) show systematic deviations. In particular, a discrepancy up to 30% has been reported for the intensities of the (3-0) band transitions detected by a pulsed cavity ring-down (CRD) spectrometer (Robie & Hodges 2006). Due to the experimental uncertainty and the pressure shift, which has not been corrected, the line positions of the (3-0) band transitions given by Bragg et al (1982) also show large discrepancies (∼10 −2 cm −1 ) compared with the calculated results taking into account the relativistic and quantum electrodynamics (QED) corrections (Komasa et al 2011).…”

“…The comparison between the experimental and calculated line intensities (Wolniewicz et al 1998;Campargue et al 2012) are shown in Figure 4. There is a systematic deviation between the present results and that by Robie & Hodges (2006), which is about two to three times the standard deviation given by Robie & Hodges (2006) for S(0), S(1), and S(3). The differences between our values and the calculated ones vary between −2% and +2%, which corresponds to the uncertainty related to the choice of the line profile function.…”

“…The line profile of the hydrogen rovibrational transitions is well known to show a remarkable Dicke narrowing that increases with the pressure (Gupta et al 2006;Robie & Hodges 2006;Kassi & Campargue 2011;Campargue et al 2012). …”

VUV-synchrotron absorption studies of N2 and CO at 900K

“…Laser-based direct excitation of the weaker (4,0) and (5,0) overtone quadrupole bands was performed in the visible domain [42]. Later investigations using cavity-ring down spectroscopy on the H 2 (3,0) overtone band were carried out by Robie et al [43] using a pulsed source and Hu et al [44,45] using a cw source. Campargue and co-workers have recently performed high-resolution determinations of the (2,0) overtone bands of H 2 [46] and D 2 [47] using quantum cascade lasers.…”