| 1. |
- Calabrese, C., et al.
(författare)
-
Laboratory rotational spectrum of acrylic acid and its isotopologues in the 6-18.5 GHz and 52-74.4 GHz frequency ranges
- 2014
-
Ingår i: Journal of Molecular Spectroscopy. - : Elsevier BV. - 0022-2852 .- 1096-083X. ; 295, s. 37-43
-
Tidskriftsartikel (refereegranskat)abstract
- In order to facilitate the detection of acrylic acid in space, for which a possible mechanism of formation is proposed, we extended the measurements of the rotational spectrum of this molecule to the 6-18.5 GHz (time domain Fourier transform) and 52-74.4 GHz (frequency domain) ranges in supersonic expansions. 77 new lines were assigned to the s-cis conformer and 83 new lines to the s-trans conformer. In addition, the rotational spectra of the three single C-13 isotopologues have been measured in natural abundance for both conformers. High resolution measurements of the carboxylic deuterated isotopologues allowed for the determination of the deuterium nuclear quadrupole coupling constants. All the spectroscopic experimental parameters were compared to the ones obtained with quantum chemical methods at the MP2(fc)/aug-cc-pVTZ and B3LYP/aug-cc-pVTZ levels of calculation.
|
|
| 2. |
|
|
| 3. |
- Hansson, Annie, et al.
(författare)
-
A comment on Hönl-London factors
- 2005
-
Ingår i: Journal of Molecular Spectroscopy. - : Elsevier Inc.. - 0022-2852 .- 1096-083X. ; 233:2, s. 169-173
-
Tidskriftsartikel (refereegranskat)abstract
- The literature on the Hönl-London factors of diatomic molecules, the factors in intensity formulas dependent on the rotational quantum numbers, is somewhat confused for the case of perpendicular transitions. We derive a formula, Eq. (23), for allowed singlet–singlet transitions between levels of definite parity, and show that it is consistent with standard sum rules. As an illustration, the formula is applied to the calculation of lifetimes in the B1Πu state of Na2, showing that the corrected formula gives results in good agreement with experimental measurements.
|
|
| 4. |
- Launila, Olli
(författare)
-
Fourier transform spectroscopy of NbS
- 2005
-
Ingår i: Journal of Molecular Spectroscopy. - : Elsevier BV. - 0022-2852 .- 1096-083X. ; 229:1, s. 31-38
-
Tidskriftsartikel (refereegranskat)abstract
- Emission bands attributed to the NbS radical have been observed in the near infrared and visible regions with FTS techniques using an electrodeless 2450 MHz discharge as a source. Transitions within the doublet and quartet manifolds were recorded at high resolution. The present paper gives the first rotational analysis of this molecule. Numerous bands within the doublet and quartet manifolds have been analyzed, resulting in the characterization of seven different electronic states, three in the doublet and four in the quartet manifold. The states have been labeled in analogy with NbO. The analyzed electronic states are: X(4)Sigma(-), C(4)Sigma(-), A'(4)Phi, D(4)Delta, a(2)Delta, c(2)Pi, and e(2)Phi. Four additional substates in the doublet manifold have also been analyzed. In all, 27 vibrational sublevels have been included in the analysis, the total number of rotational lines being about 18000. The positions of the analyzed transitions are: C(4)Sigma(-) --> X(4)Sigma(-) near 15670 cm(-1), D(4)Delta --> A'(4)Phi near 7740 cm(-1), c(2)Pi --> a(2)Delta near 5850 cm(-1) and e(2)Phi --> a(2)Delta near 8500 cm(-1). The overall picture is consistent with the corresponding analysis of NbO. However, three energy separations could not be derived from the experimental data in the case of NbS, i.e., the a(2)Delta - X(4)Sigma(-), A'(4)Phi - X(4)Sigma(-) and a(2)Delta(5/2) - a(2)Delta(3/2) splintings. These were set to 4992, 5490, and 992 cm(-1), respectively, from preliminary ab initio calculations. In this way, a tentative energy level scheme could be drawn. The first order spin-orbit parameter of the A'(4)Phi state was indeterminable from the experimental data and was set to the value 170 cm(-1), derived from the same calculations.
|
|
| 5. |
- Launila, Olli
(författare)
-
On the spin and hyperfine splittings in the X(2)Sigma(+) ground states of AlO and AlS
- 2012
-
Ingår i: Journal of Molecular Spectroscopy. - : Elsevier BV. - 0022-2852 .- 1096-083X. ; 271:1, s. 56-58
-
Tidskriftsartikel (refereegranskat)abstract
- A re-analysis of the A'(2)Pi(i)-X(2)Sigma(+) band system of the AlS radical has been performed. The previously published material has been refined and extended to approximately 36,000 line assignments. The line material has been fitted to a(2)Sigma(+) hyperfine Hamiltonian, in the same manner as in the recently published work on the B(2)Sigma(+)-X(2)Sigma(+) and A(2)Pi(i)-X(2)Sigma(+) systems of AlO. The present analysis shows the same trends for the ground state gamma-values as in AlO, i.e. decreasing gamma-values upon increasing v. It has been confirmed that the spin splittings of the X(2)Sigma(+) (v=0) levels in both molecules are mainly due to nuclear hyperfine interaction and second order spin-orbit effects due to the high-lying regular (2)Pi state (C(2)Pi in AlO and B(2)Pi in AlS), while the influence of the low-lying inverted (2)Pi state on gamma increases dramatically with increasing v, resulting in negative gamma-values starting from v=2.
|
|
| 6. |
- Launila, Olli, et al.
(författare)
-
Spectroscopy of AlO : Combined analysis of the A(2)Pi(i) -> X-2 Sigma(+) and B-2 Sigma(+) -> X-2 Sigma(+) transitions
- 2011
-
Ingår i: Journal of Molecular Spectroscopy. - : Elsevier BV. - 0022-2852 .- 1096-083X. ; 265:1, s. 10-14
-
Tidskriftsartikel (refereegranskat)abstract
- A combined analysis of the A(2)Pi(i) -> X-2 Sigma(+) and B-2 Sigma(+) -> X-2 Sigma(+) band systems of AlO, involving 21,500 line assignments, has been performed. The analysis indicates that the previously reported gamma values of the B-2 Sigma(+) state are questionable. The present analysis shows that gamma(B-2 Sigma(+))approximate to 0.014 cm(-1), essentially independent of the vibrational level. The positive sign is consistent with second order interaction with the higher-lying C-2 Pi(r) and lower-lying A(2)Pi(i) states. It also appears that many of the previously reported gamma and gamma(D) values of X-2 Sigma(+) (v > 0) are doubtful. In fact, gamma(X-2 Sigma(+)) is observed to become increasingly negative for v '' > 1, due to second order interaction with the low-lying A(2)Pi(i) state. The present results are based on models where the hyperfine structure of the (2)Sigma(+) states has been taken into account explicitly. Intensity patterns of the branches of the B-2 Sigma(+) -> X-2 Sigma(+) system have been shown to be influenced by the case b beta(s) coupling in the ground state v = 0,1 levels. This gives rise to intensity differences of around 10 percent in the R-1/R-2 and P-1/P-2 doublet components. The synthesized intensity patterns are fully in accord with the F-1/F-2 assignments of the present work.
|
|
| 7. |
- Linnartz, H., et al.
(författare)
-
C-60(+) as a diffuse interstellar band carrier; a spectroscopic story in 6 acts
- 2020
-
Ingår i: Journal of Molecular Spectroscopy. - : Elsevier BV. - 0022-2852 .- 1096-083X. ; 367
-
Tidskriftsartikel (refereegranskat)abstract
- In 2019 it was exactly 100 years ago that the first two DIBs, diffuse interstellar bands, were discovered by Mary Lea Heger. Today some 500 + DIBs are known. In numerous observational, modelling and laboratory studies, efforts have been made to identify the carriers of these absorption features that are observed in the light of reddened stars crossing diffuse and translucent clouds. Despite several claims over the years that specific DIBs could be assigned to specific species, not one of these withstood dedicated follow-up studies. An exception is C-60(+). In 2015, Campbell et al. showed that two strong bands, recorded in the laboratory around 960 nm, coincided precisely with known DIBs and in follow-up studies three more matches between C-60(+) transitions and new observational DIB studies were claimed. Over the last four years the evidence for C-60(+) as the first identified DIB carrier - including new laboratory data and Hubble Space Telescope observations - has been accumulating, but not all open issues have been solved yet. This article summarizes 6 spectroscopic achievements that sequentially contributed to what seems to become the first DIB story with a happy end.
|
|
| 8. |
- Liu, M., et al.
(författare)
-
Time-resolved study of the A(2)Pi state of CaH by laser spectroscopy
- 2009
-
Ingår i: Journal of Molecular Spectroscopy. - : Elsevier BV. - 0022-2852 .- 1096-083X. ; 257:1, s. 105-107
-
Tidskriftsartikel (refereegranskat)abstract
- A time-resolved experiment on the A(2)Pi state of gaseous calcium hydride has been performed by applying laser spectroscopic methods. The following zero-pressure lifetime was obtained for the CaH A(2)Pi state: tau(nu=0) = 33.2 (+/- 3.2) ns and tau(nu=1) = 33.7 (+/- 5.2) ns. The lifetime was found to be the same for the A(2)Pi(1/2) and Delta(2)Pi(3/2) states.
|
|
| 9. |
- Marimuthu, Aravindh N., et al.
(författare)
-
Laboratory gas-phase vibrational spectra of [C3H3]+ isomers and isotopologues by IRPD spectroscopy
- 2020
-
Ingår i: Journal of Molecular Spectroscopy. - : Elsevier BV. - 0022-2852 .- 1096-083X. ; 374
-
Tidskriftsartikel (refereegranskat)abstract
- Gas phase vibrational spectra of [C3H3]+ isomers and their fully deuterated isotopologues measured in a cryogenic 22-pole ion trap are presented. The widely tunable free electron laser for infrared experiments, FELIX, was employed to cover the frequency range 500–2400 cm−1, complemented with an OPO/OPA system covering 2800–3400 cm−1. Spectral assignments for both the linear and cyclic isomeric form (H2C3H+ and c-C3H3+, respectively) are made based on various high-level computational studies. The effect of ion source conditions and different precursors (allene and propargyl chloride) for the preferential production of a specific isomer is discussed. The perturbation of the vibrational band position due to complexation with neon in the recorded infrared-predissociation (IRPD) spectra are also reported in this study.
|
|
| 10. |
|
|
