Transition frequencies in the (2-0) band of D2 with MHz accuracy

Abstract

Series of spectra of the S(0) and Q(1)-Q(4) transitions of the (2-0) band of D 2 near 5860 cm -1 are recorded by comb-referenced cavity ring down spectroscopy at four pressures up to 200 Torr. After averaging, high resolution (30 MHz step) and low noise (noise equivalent absorption,  min ≈ 1.5×10 -11 cm -1 ) spectra are obtained for each pressure value. This leads to signal to noise ratios of several hundred for the considered very weak electric quadrupole transitions with intensities ranging between 4×10 -29 and 4×10 -28 cm/molecule. The Q(3) and Q(4) transitions are newly detected.A multi-spectrum treatment of the D 2 line profiles at different pressures performed using a quadratic speed-dependent Nelkin-Ghatak profile leads to residuals close to the noise level. Considering statistical fit errors and possible biases, total uncertainties on the frequencies extrapolated at zero pressure are estimated between 0.30 MHz and 1.83 MHz.The derived experimental frequencies and intensities of (2-0) transitions are gathered with literature values and compared to ab initio values reported in

Stimulated Raman scattering metrology of molecular hydrogen

“…Many experiments circumvented this weakness using high-finesse optical cavities providing enhancement of the effective absorption length up to several kilometers 10 . Thanks to the comb referencing of the frequency of the cavity-injected laser, transition frequencies have been measured with uncertainties of few parts per billion (ppb) [11][12][13][14][15][16] , at the same level of ab initio calculations 4 . The main limiting factors are the signal-to-noise ratio at low pressures and the nontrivial extrapolation of the line center to zero pressure because of the complexity of absorption lineshapes 17 .…”

Cavity Ring-Down Spectroscopy: Recent Technological Advancements, Techniques, and Applications

“…Such studies actively contribute to the construction of empirical molecular databases and also serve to improve the theoretical calculations for transition line parameters . The same group reported the accurate line parameters for very weak transitions in the first overtone band of D 2 to validate the quantum electrodynamic (QED) corrections in the theoretical calculations for these parameters . HD is another simple molecule whose spectra are extensively studied to compare with higher order corrections in theory including QED and relativistic effects.…”

“…23 The same group reported the accurate line parameters for very weak transitions in the first overtone band of D 2 to validate the quantum electrodynamic (QED) corrections in the theoretical calculations for these parameters. 26 HD is another simple molecule whose spectra are extensively studied to compare with higher order corrections in theory including QED and relativistic effects. With such a motive, the weak R(1) transition of HD in its overtone band was probed using CE-OFC technique with an uncertainty of ∼100 kHz with subsequent determination of the line parameters.…”

Hyperfine components of all rovibrational quadrupole transitions in the H$_{2}$ and D$_{2}$ molecules

“…Theoretical studies of the rovibrational structure of the ground electronic state in molecular hydrogen achieve remarkable accuracy in the determined dissociation energy [1][2][3][4][5] and rovibrational energy levels [6][7][8][9][10][11][12]. The progress in the theoretical investigations is enhanced by recent experiments, which aim at the sub-MHz accuracy of both the dissociation energy [13,14] and the rovibrational transition frequencies in the ground electronic state [15][16][17][18][19][20][21][22][23][24][25][26][27]. Comparison between theoretical calculations and accurate measurements can be used as a test for the quantum electrodynamics for molecules [12], determination of the proton-charge radius [1,8,13,14] or even searches for physics beyond Standard Model [28], i.e.…”

“…The first overtone in D 2 was also recently studied by Wójtewicz et al [24], who reported 870 and 999 kHz combined uncertainties for the positions of the S(3) and S(4) lines, respectively. Mondelain et al [25], estimated the uncertainty of the frequencies of the S(0) and Q(1)-Q(4) D 2 transitions between 0.3 and 1.83 MHz. In the case of the H 2 molecule, the most accurate measurements that probed rovibrational levels directly, reached the accuracy of 6.6 MHz [35], while measurements based on subtraction of the energies of two electronic transitions achieved the accuracy of 4.5 MHz [15,36] for ν = 0, N = 0 and ν = 1, N = 0 states and 1.5 MHz [22] for the ν = 0, N = 0 and ν = 0, N = 1 states.…”