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- Burmeister, F., et al.
(författare)
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A study of the inner-valence ionization region in HCl and DCl
- 2004
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Ingår i: Journal of Physics B. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 37:6, s. 1173-1183
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Tidskriftsartikel (refereegranskat)abstract
- An in-depth photoionization study of the inner-valence electrons in HCl and DCl has been performed using synchrotron radiation. A series of photoelectron spectra of HCl were obtained at a resolution of 23 meV over the binding energy range 25-30.5 eV at various excitation energies and at two different electron collection angles relative to the plane of polarization of the undulator radiation. In addition, photoelectron spectra of DCl were recorded at two different excitation energies. These spectra were compared directly with the threshold photoelectron spectra of HCl and DCl that were recorded previously under similar resolution conditions (similar to30 meV). This comparative study reveals new information on the nature of the numerous band systems observed in this binding energy region. In addition, we present the experimental confirmation of the theoretical prediction given by Andersson et al (2001 Phys. Rev. A 65 012705) that a vibrational progression showing interference structure would appear in the main inner-valence ionization band in the photoelectron spectrum of DCl at a resolution of 10 meV.
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| 5. |
- Kolczewski, C., et al.
(författare)
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Detailed study of pyridine at the C1s and N1s ionization thresholds : The influence of the vibrational fine structure
- 2001
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 115:14, s. 6426-6437
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Tidskriftsartikel (refereegranskat)abstract
- High resolution, vibrationally resolved, near-edge x-ray absorption fine structure (NEXAFS) spectra at the C 1s and N 1s ionization thresholds of pyridine and deuterated d(5)-pyridine in the gas phase have been recorded. The high resolution of 65 meV (150 meV) at the C s (N 1s) ionization thresholds reveals vibrational structures in the spectra. Detailed ab initio and density functional theory (DFT) calculations were performed to interpret the experimental spectra and to assign the observed peaks. In particular we focused on the previously unexplained intensity ratio for the two components of the C1s -->1 pi* transition. For this transition the vibrational structure is included through a linear coupling model in the DFT calculations and leads to the experimentally observed similar to2:3 intensity ratio between the two pi* components in the C1s spectrum rather than the similar to3:2 ratio obtained without vibrational effects. After inclusion of relaxation effects in the excited states, in addition to the vibrational effects, both theoretical methods yield almost perfect agreement with experiment.
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| 6. |
- Sonderegger, M, et al.
(författare)
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Fermentation performance of engineered and evolved xylose-fermenting Saccharomyces cerevisiae strains
- 2004
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Ingår i: Biotechnology and Bioengineering. - : Wiley. - 1097-0290 .- 0006-3592. ; 87:1, s. 90-98
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Tidskriftsartikel (refereegranskat)abstract
- Lignocellulose hydrolysate is an abundant substrate for bioethanol production. The ideal microorganism for such a fermentation process should combine rapid and efficient conversion of the available carbon sources to ethanol with high tolerance to ethanol and to inhibitory components in the hydrolysate. A particular biological problem are the pentoses, which are not naturally metabolized by the main industrial ethanol producer Saccharomyces cerevisiae. Several recombinant, mutated, and evolved xylose fermenting S. cerevisiae strains have been developed recently. We compare here the fermentation performance and robustness of eight recombinant strains and two evolved populations on glucose/xylose mixtures in defined and lignocellulose hydrolysate-containing medium. Generally, the polyploid industrial strains depleted xylose faster and were more resistant to the hydrolysate than the laboratory strains. The industrial strains accumulated, however, up to 30% more xylitol and therefore produced less ethanol than the haploid strains. The three most attractive strains were the mutated and selected, extremely rapid xylose consumer TMB3400, the evolved C5 strain with the highest achieved ethanol titer, and the engineered industrial F12 strain with by far the highest robustness to the lignocellulosic hydrolysate. (C) 2004 Wiley Periodicals, Inc.
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