“…The He-broadening of CO transitions was also extensively studied [4,5,8,13,[15][16][17][18][19][20][21][22][23][24][25] because this case is relevant to determining the composition of interstellar molecular clouds and the atmospheres of the outer planets. Also, many other rare gases have been considered as collision partners to investigate how CO line shapes depend on the perturber-to-absorber mass ratio [4,5,7,13,16,19,20,23,[26][27][28][29][30][31][32][33][34][35][36]. All of these studies indicate that measured CO line shapes deviate from the often-used Voigt profile.…”