Low-energy electron scattering by cellulose and hemicellulose components

Abstract

We report elastic integral, differential and momentum transfer cross sections for low-energy electron scattering by the cellulose components β-D-glucose and cellobiose (β(1 → 4) linked glucose dimer), and the hemicellulose component β-D-xylose. For comparison with the β forms, we also obtain results for the amylose subunits α-D-glucose and maltose (α(1 → 4) linked glucose dimer). The integral cross sections show double peaked broad structures between 8 eV and 20 eV similar to previously reported results for tetrahydrofuran and 2-deoxyribose, suggesting a general feature of molecules containing furanose and pyranose rings. These broad structures would reflect OH, CO and/or CC σ* resonances, where inspection of low-lying virtual orbitals suggests significant contribution from anion states. Though we do not examine dissociation pathways, these anion states could play a role in dissociative electron attachment mechanisms, in case they were coupled to the long-lived π* anions found in lignin subunits [de Oliveira et al., Phys. Rev. A, 2012, 86, 020701(R)]. Altogether, the resonance spectra of lignin, cellulose and hemicellulose components establish a physical-chemical basis for electron-induced biomass pretreatment that could be applied to biofuel production.

Theoretical and experimental study on electron interactions with chlorobenzene: Shape resonances and differential cross sections

“…However, the present SEP+Born calculations differ from the Born-dipole model of Ref. 22, since (i) we account for short-range (other than dipole) interactions in the lower partial waves, which would be important for scattering at higher angles; (ii) our Born corrections employ an overestimated dipole moment magnitude (consistent with the HF description of the target molecule); (iii) our model amounts to an approximate rotationally summed cross section from the rotational ground state of the target, without accounting for thermal averages over the initial rotational states (see Oliveira et al 47 for details); and (iv) we do not correct the cross sections to account for undetected electrons at low scattering angles as described by Lunt et al, 22 although we integrate the Regarding the resonances, the lowest-lying structure in the SMCPP ICS, about 0.7 eV, is related to the nearly degenerate π * (B 1 ) and π * (A 2 ) resonances (see below). The peak position agrees with the experimental TCS 22,23 (0.75 and 0.8 eV, respectively), as well as with the ETS data 14,15 (0.73 eV-0.75 eV) and the DEA data 14,[16][17][18] (∼0.7 eV).…”

“…When dealing with molecules that possess a permanent electric dipole moment, the long-range character of the dipole potential is truncated by the range of the Cartesian Gaussian functions, and as a consequence, the higher partial waves are not correctly described. To investigate the impact of long-range interactions on the present calculations, we included the dipole potential through a closure procedure described by Oliveira et al 47 With this procedure, the lower partial waves of the scattering amplitude are computed with the SMC method (we will call l SMC the highest partial wave considered from the SMC method) and the higher partial waves are computed with a scattering for the dipole moment potential of the molecule computed in the first Born approximation. 47 The number of lower partial waves included in the calculation depends on the impact energy and is chosen in order to provide the DCSs obtained with and without the Born closure correction in agreement at medium and higher scattering angles.…”

“…To investigate the impact of long-range interactions on the present calculations, we included the dipole potential through a closure procedure described by Oliveira et al 47 With this procedure, the lower partial waves of the scattering amplitude are computed with the SMC method (we will call l SMC the highest partial wave considered from the SMC method) and the higher partial waves are computed with a scattering for the dipole moment potential of the molecule computed in the first Born approximation. 47 The number of lower partial waves included in the calculation depends on the impact energy and is chosen in order to provide the DCSs obtained with and without the Born closure correction in agreement at medium and higher scattering angles. For the calculations in the SEP approximations, we employed l SMC = 3 for energies up to 1.5 eV, l SMC = 4 from 1.6 eV to 3.5 eV, l SMC = 5 from 4.0 to 5.8 eV, l SMC = 6 from 5.9 to 7.5 eV, and l SMC = 7 from 8.0 to 12 eV.…”

Low-energy elastic electron scattering from isobutanol and related alkyl amines

“…We considered single virtual excitations of the target, considering both singletand triplet-coupled excitations, from the 16 occupied orbitals to the lowest 26 IVOs, giving the total of 11 011 configuration state functions in the expansion of the scattering wave function. We employed the standard Born-closure procedure [26] to account for scattering of the higher partial waves due to the long-range character of the dipole potential.…”

Recent advances in the application of the Schwinger multichannel method with pseudopotentials to electron-molecule collisions

“…Some of the examples are: (1) planetary atmospheres bombarded by photons and charged particles [1,2], (2) practical understanding of atmospheric reentry physics in space programs [3], (3) modeling of chemical plasmas for surface treatments [4][5][6][7], (4) DNA fragmentation induced by electron attachment (motivation for studying several biomolecules) [8], (5) nanomaterials fabrication using focused electron-beam-induced processing [9,10] and more recently (6) pre-treatment (de-lignification) of biomass to obtain biofuels [11][12][13].…”