| 1. |
- Davidsson, A., et al.
(författare)
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On the problem of obtaining accurate circular dichroism. Calibration of circular dichroism spectrometers
- 1976
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Ingår i: Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy. - : Elsevier BV. - 1386-1425 .- 0584-8539. ; 32:4, s. 717-722
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Tidskriftsartikel (refereegranskat)abstract
- It is questioned whether common circular dichroism (CD) spectrometers can be relied upon if they are calibrated at a single wavelength only. A procedure for obtaining the influence of certain instrumental parameters is described, and relations are given to correct the CD.This discussion was found relevant on examination of a particular commercial CD spectrometer for which fairly large corrections were necessary. It is suggested that the different values reported for two common CD standards may be explained by errors of the type considered, in different instruments.
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| 2. |
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| 3. |
- Nordén, Bengt, 1945
(författare)
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Low temperature circular dichroism artifacts. Birefringence-free cryostat
- 1976
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Ingår i: Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy. - : Elsevier BV. - 1386-1425 .- 0584-8539. ; 32:2, s. 441-442
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Attention is called to the risks of neglecting regular checking of the optical function of CD cryostat windows. A sensitive birefringence test and a flexible window seat construction are described.
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| 4. |
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| 5. |
- Bai, Xiao, et al.
(författare)
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Absorption of formaldehyde (H2CO) in the (A)over-tilde(1)A(2)
- 2004
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Ingår i: Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy. - 1386-1425. ; 60:4, s. 821-828
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Tidskriftsartikel (refereegranskat)abstract
- The electronic A(1)A(2) <-- X(1)A(1) absorption spectra of formaldehyde vapour were studied at temperatures varying from 423 to 770 K with variable pressures from less than 0.1 to 1 MPa. Broadband vibronic and partially rotationally resolved 4(n)(1) rovibronic spectra of formaldehyde showed considerable sensitivity to temperature. The high resolution spectra showed collision-induced broadening as the pressure was increased. The results show that the absorption efficiency of the laser radiation front the third harmonic of Nd:YAG lasers is sensitive to the spectral properties of the laser, such as line position and shape. Promising results were obtained from the comparison between theoretical and measured absorption spectra.
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| 6. |
- Brackmann, Christian, et al.
(författare)
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Laser-induced fluorescence of formaldehyde in combustion using third harmonic Nd : YAG laser excitation
- 2003
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Ingår i: Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy. - 1386-1425. ; 59:14, s. 3347-3356
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Tidskriftsartikel (refereegranskat)abstract
- Formaldehyde (CH2O) is an important intermediate species in combustion processes and it can through laser-induced fluorescence measurements be used for instantaneous flame front detection. The present study has focussed on the use of the third harmonic of a Nd:YAG laser at 355 nm as excitation wavelength for formaldehyde, and different dimethyl ether (C2H6O) flames were used as sources of formaldehyde in the experiments. The investigations included studies of the overlap between the laser profile and the absorption lines of formaldehyde, saturation effects and the potential occurrence of laser-induced photochemistry. The technique was applied for detection of formaldehyde in an internal combustion engine operated both as a spark ignition engine and as a homogenous charge compression ignition engine. (C) 2003 Elsevier B.V. All rights reserved.
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| 7. |
- Hammarstrom, L., et al.
(författare)
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A biomimetic approach to artificial photosynthesis : Ru(II)-polypyridine photo-sensitisers linked to tyrosine and manganese electron donors
- 2001
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Ingår i: Spectrochimica Acta Part A - Molecular and Biomolecular Spectroscopy. - 1386-1425 .- 1873-3557. ; 57:11, s. 2145-2160
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Forskningsöversikt (refereegranskat)abstract
- The paper describes recent advances towards the construction of functional rr mics of the oxygen evolving complex in photosystem II (PSII) that are coupled to photoinduced charge separation. Some key principles of PSII and artificial systems for light-induced charge accumulation are discussed. Systems are described where biomimetic electron donors - manganese complexes and tyrosine - have been linked to a Ru(II)-polypyridine photosensitiser. Oxidation of the donors by intramolecular electron transfer from the photo-oxidised Ru(III) complex has been studied using optical flash photolysis and EPR experiments. A step-wise electron transfer Mn-2(III,III) --> tyrosine --> Ru(III) has been demonstrated, in analogy to the reaction on the donor side of PSII Electron transfer from the tyrosine to Ru(III) was coupled to tyrosine deprotonation. This resulted in a large reorganisation energy and thus a slow reaction rate, unless the tyrosine was hydrogen bonded or already deprotonated. A comparison with analogous reactions in PSH is made. Finally, light-induced oxidation of a manganese dimer linked to a Ru(II)-photosensitiser has been observed. Preliminary results suggest the possibility of photo-oxidising manganese dimers in several steps, which is an important advancement towards water oxidation.
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| 8. |
- Jensen, PS, et al.
(författare)
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Determination of urea, glucose, and phosphate in dialysate with Fourier transform infrared spectroscopy
- 2004
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Ingår i: Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy. - 1386-1425. ; 60:4, s. 899-905
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Tidskriftsartikel (refereegranskat)abstract
- Individual control and quantification of phosphate removal is desirable in dialysis treatment. Currently, no on-line method exists to quantify phosphate removal. We demonstrate that a multivariate calibration model based on infrared transmission spectra is capable of predicting phosphate, urea, and glucose concentrations at clinically relevant levels. The on-line monitoring of these components by infrared spectroscopy is therefore feasible. (C) 2003 Elsevier B.V. All rights reserved.
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| 9. |
- Metz, Thomas, et al.
(författare)
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Fluorescence lifetimes of formaldehyde (H2CO) in the (A)over-tilde(1)A(2) -> (X)over-tilde(1)A(1) band system at elevated temperatures and pressures
- 2004
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Ingår i: Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy. - 1386-1425. ; 60:5, s. 1043-1053
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Tidskriftsartikel (refereegranskat)abstract
- Fluorescence lifetimes of formaldehyde excited by picosecond laser radiation with a wavelength of 355 nm were determined in nitrogen gas in a cell using time-resolved laser-induced fluorescence spectroscopy. The measurements were conducted at temperatures between 295 and 770 K and pressures up to 10 bar (1 MPa). Detection was broadband in most cases. Temperature and pressure were found to have a quenching effect on the fluorescence. At 295 K and pressures between 1 and 5 bar, decay rates between 0.03 and 0.04 ns(-1) were observed. At 770 K, the decay rates increased from 0.11 to 0.17 ns(-1) as the pressure was raised from 1 to 10 bar. The dependence on pressure was not linear at 1 bar. At 10 bar the linearity is unclear. The dependence on temperature appeared to be exponential. (C) 2003 Elsevier B.V. All rights reserved.
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| 10. |
- Mikulskiene, Birute, et al.
(författare)
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On the stability of the hydrogen chloride complexes with ethylene and acetylene. A high resolution gas phase and ab initio study
- 2003
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Ingår i: Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy. - 1386-1425. ; 59:4, s. 733-741
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Tidskriftsartikel (refereegranskat)abstract
- The temperature dependencies of the intensities of the HCl stretching bands of the hydrogen chloride complexes with acetylene and ethylene have been used to obtain estimates of the dissociation enthalpies of the two complexes. Quantum chemical calculations on the Hartree Fock and DFT/B3LYP levels of theory have been combined with experimental data to give estimates of the intensities of the HCl stretching vibration in the two complexes.
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