ner_tags: O O B-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength O O B-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength O B-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength O O O O B-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength O O O O B-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength O O O O O B-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength O O O O B-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength O O O O B-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength O O O O O B-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O
tokens: collisions with para -H 2 ( j 2 = 0). We also observe that the relative magnitudes of the rate coefficients for the transitions to the 1 01 level are different in Figs 2(a) and (b) . Figure 2. Rate coefficients as a function of temperature for de-excitation transitions to the final 1 01 level of ortho -H 2 S in collisions with (a) para -H 2 ( j 2 = 0) and (b) ortho -H 2 ( j 2 = 1). The initial levels are indicated on the plots. Comparing the plots in Figs 1(a) and 2(a) and the plots in Figs 1(b) and 2(b) , we see that for these lower rotational levels the rate coefficients for collision-induced transitions in ortho -H 2 S are somewhat larger than those in para -H 2 S. 4 DISCUSSION Since H 2 O–H 2 rate coefficients have been used as surrogates for H 2 S–H 2 rate coefficients (Crockett et al. 2014 ; Vastel et al. 2018 ), it is interesting to compare the overall magnitudes of these two sets of rate coefficients. Fig. 3 compares the rate coefficients for de-excitation transitions in ortho -H 2 O and ortho -H 2 S induced by collisions with para -H 2 ( j 2 = 0) and ortho -H 2 ( j 2 = 1) at temperatures of 5 and 100 K. Fig. 4 presents a similar comparison for para -H 2 O and para -H 2 S rate coefficients. The rate coefficients for H 2 S–H 2 collisions are taken from this work, while those for H 2 O–H 2 collisions were obtained from the work by Daniel et al. ( 2011 ). Figure 3. Comparison of de-excitation rate coefficients between the 12 lowest rotational levels of ortho -H 2 O and ortho -H 2 S in collisions with (a) para -H 2 ( j 2 = 0) at 5 K, (b) para -H 2 ( j 2 = 0) at 100 K, (c) ortho -H 2 ( j 2 = 1) at 5 K, and (d) ortho -H 2 ( j 2 = 1) at 100 K. The solid line denotes equal rate coefficients for ortho -H 2 O and ortho -H 2 S, while the dashed lines represent a factor of 2 difference in the rate coefficients. Figure 4. Comparison of de-excitation rate coefficients between the 12 lowest rotational levels of para -H 2 O and para -H 2 S in collisions with (a) para -H 2 ( j 2 = 0) at 5 K, (b) para -H 2 ( j 2 = 0) at 100 K, (c) ortho -H 2 ( j 2 = 1) at 5 K, and (d) ortho -H 2 ( j 2 = 1) at 100 K. The solid line denotes equal rate coefficients for para -H 2 O and para -H 2 S, while the dashed lines represent a factor of 2 difference in the rate coefficients. We see in both Figs 3 and 4 that the transitions in H 2 O with the largest rate coefficients are greater in magnitude than the corresponding transitions in H 2 S, that is to say, the points in upper right-hand corner of these figures are to the right of the solid diagonal line. These differences reflect the different topologies of the H 2 O and H 2 S PES. By contrast, for H 2 S–H 2 transitions with smaller rate coefficients, i.e. those lying on the left-hand side of the plots in these figures, are larger than the rate coefficients for the corresponding transitions in H 2 O–H 2 . It should be noted that the energy spacings in H 2 S are smaller than in H 2 O since the rotational constants for the