Total cross section measurements for electron scattering from dichloromethane

Abstract

Using our magnetically confined electron transmission apparatus, we report the results of total cross sections (TCSs) for electron scattering from dichloromethane (CH 2 Cl 2). The energy range of this study is 1-300 eV. Wherever possible, the present data are compared to earlier measured TCSs of Wan et al. [J. Chem. Phys. 94, 1865 (1991)] and Karwasz et al. [Phys. Rev. A 59, 1341 (1999)] and to the corresponding theoretical independent atom model with screening corrected additivity rule and interference term (IAM-SCAR+I) results of Krupa et al. [Phys. Rev. A 97, 042702 (2018)] and a spherical complex optical potential formulation calculation of Naghma et al. [J. Electron Spectrosc. Relat. Phenom. 193, 48 (2014)]. Within their respective uncertainties, the present TCS and those of Karwasz et al. are found to be in very good agreement over their common energy range. However, agreement with the results of Wan et al. is quite poor. The importance of the experimentally inherent 'missing angle' effect (see later) on the measured TCS is investigated and found to be significant at the lower energies studied. Indeed, when this effect is accounted for, agreement between our measured TCSs and the corrected IAM-SCAR+I+rotations calculation results are, for energies above about 3 eV, in good accord (to better than 8%). Finally, we observe two σ * shape resonances, consistent with the earlier electron transmission spectroscopy results of Burrow et al. [J. Chem. Phys. 77, 2699 (1982)], at about 2.8 eV and 4.4 eV incident electron energy, in our measured TCS.

Recent total cross section measurements in electron scattering from molecules

“…Dichloromethane (DCM) is an organic compound widely used as a solvent for many chemical processes. Though, 124 125 Fig. 19.…”

“…Molecular targets, and references in the text Baylor University, C2H4 (ethylene), C3H6 (propene), C4H8 (butene), C4H6 (1,3-butadiene) [144]; Waco, USA C2H2 (acetylene), C3H4 (propyne) [145] Gdańsk University HCOOH (formic acid) [86]; C4H4O (furan) [87]; C3H3NO (isoxazole) [90]; of Technology, C5H5N (pyridine) [107]; C5H10O (tetrahydropyran) [111]; Gdańsk, Poland (CH3)2CO (acetaldehyde) [116]; (CF3)2CO (hexafluoroacetone) [117]; X(CH3)4 (X=C,Si,Ge) [126]; SnCl4 [127]; C4H8 (1-butene, 2-methylpropene) [136]; C5H10 (1-pentene) [138]; C5H10 (2-methyl-2-butene), C6H12 (2,3-dimethyl-2-butene) [137]; C2H2 (acetylene), C4H6 (1-butyne) [139]; C4H6 (1,2-butadiene) [141]; C5H6 (2-methyl-1-buten-3-yne) [142]; C5H8 (2-methyl-1,3-butadiene) [143] Institute of Technology, N2 (nitrogen) [62]; O2 (oxygen) [71] Tokyo, Japan Instituto de Matemáticas N2 (nitrogen) [63]; CH2Cl2 (dichloromethane) [124] y Fisica Fundamental, C4H4S (thiophene) [88]; C5H4O2 (furfural) [89]; C4H8O (tetrahydrofuran) [94]; (CSIC), Madrid, Spain C6H6 (benzene) [98]; C6H5OH (phenol) [103]; C5H5N (pyridine) [105,106]; C4H4N2 (pyrimidine) [109]; C4H4N2 (pyrazine) [110]; C6H4O2 (para-benzoquinone) [112]; C4H3F7O (sevoflurane) […”

“…19. Comparison of experimental grand-total cross sections for dichloromethane • [124] and chloromethane ∎ [125].…”

“…the majority of dichloromethane in the environment comes from industrial emissions, there are also its natural sources. Figure 19 depicts electron-scattering absolute grandtotal cross section for the CH 2 Cl 2 molecule measured by Lozano et al [124] over the energy range 1-300 eV. To examine how the substitution of hydrogen atoms with chlorine in methane molecule reflects in the TCS energy dependence, in Figure 19 TCS results for chloromethane [125] are also included.…”

The electronic excited states of dichloromethane in the 5.8-10.8 eV energy range investigated by experimental and theoretical methods

“…CH2Cl2 has been investigated by various experimental methods that seek to elucidate its physico-chemical properties. These include bond lengths and geometry [7], ultraviolet photoabsorption [8][9][10][11][12][13][14] and photodissociation [15,16], photon and multiphoton ionisation [17][18][19], photoelectron spectroscopy [20,21], photo-oxidation [22,23] and electron impact spectroscopies [24][25][26][27][28][29][30][31][32][33][34], with the most recent electron scattering measurement reported by Hlousek et al [35] and the Madrid group [36] (and references therein), with a particular focus on elastic differential cross sections and its grand total cross section, respectively. We also note that dichloromethane has been explored by several theoretical methods with studies investigating its molecular orbitals and geometry [10,37,38], calculations on the vertical excitation energies of its neutral molecule [10] and photodissociation [39].…”