High-resolution Fourier-transform spectroscopy and deperturbation analysis of the A¹Π(v = 1) level in ¹²C¹⁸O

The A1Π(v = 1) level of the 12C18O isotopologue was precisely reinvestigated with two complementary spectroscopic techniques. High resolution B1Σ+ → A1Π(0, 1), (1, 1) and C1Σ+ → A1Π(0, 1) emission bands were recorded in the visible region, 20,700 – 26,100 cm−1, with a 1.71 m Fourier-transform spectrometer (Bruker IFS 125-HR) installed at the University of Rzeszów. The resulting line centre accuracy of isolated and medium to strong lines is 0.005 cm−1. In addition, high-resolution spectra of the A1Π ⟵ X1Σ+(1, 0), B1Σ+⟵ X1Σ+(0, 0) and (1, 0) as well as C1Σ+⟵ X1Σ+(0, 0) bands were recorded between 66,200 and 95,250 cm−1 using the vacuum-ultraviolet Fourier-transform spectrometer installed at the DESIRS beamline of the SOLEIL synchrotron. The wavenumber accuracy for isolated and strong spectral lines is 0.01 cm−1. A data set of 626 spectral lines belonging to seven bands was incorporated into a global deperturbation analysis. Significantly improved deperturbed molecular constants for the A1Π(v = 1), a´3Σ+(v = 10), D1Δ(v = 1), and I1Σ−(v = 2) levels, term values of the B1Σ+(v = 0, 1) and C1Σ+(v = 0) Rydberg states as well as the accompanying spin-orbit and rotation-electronic (L-uncoupling) interaction parameters were obtained. The experimental ro-vibrational term values of the A1Π(v = 1) level and its perturbers were also determined. The mixed composition of interacting states is expressed in terms of their 1Π percentage character

Data for: High-resolution Fourier-transform spectroscopy and deperturbation analysis of the A1Π(v = 1) level in 12C18O.

Data for: High-resolution Fourier-transform spectroscopy and deperturbation analysis of the A1Π(v = 1) level in 12C18O. Log file of the final 12C18O deperturbation fit together with line list, results (constants and terms with uncertainties) and correlation matrix

Reanalysis of the Ångström System (B1Σ+−A1Π)(B^1 Σ^{+} - A^1 \Pi) in the 13C16O\text{}^{13}C^{16}O Isotopic Molecule

The emission spectrum of the Ångström system $(B^1 Σ^{+} - A^1 \Pi)$ of $\text{}^{13}C^{16}O$ was obtained under high resolution with an accuracy estimated to be ± 0.002 $cm^{-1}$ as an emission spectrum using a high accuracy dispersive optical spectroscopy. The light source was a hollow-cathode lamp with two anodes built in our laboratory, with a previously deposited small quantity of $\text{}^{13}C$ carbon on the electrodes. The emission from the discharge was observed with a plane grating spectrograph and recorded by a photomultiplier tube. In total 195 transition wave numbers belonging to the strongest 0-1 and 0-2 bands of the B - A system were precisely measured. The modern rotational reanalysis made it possible to verify the molecular information for the both combining states of the Ångström system. In particular the rovibrational constants for the $B^1 Σ^{+}$ Rydberg state have been significantly improved ($B_0$ = 1.8625054(65) $cm^{-1}$ and $D_0=6.1384(52) \times 10^{-6} cm^{-1}$) and the obtained equilibrium rotational constants of this state are more accurate than known to date. Numerous rotational perturbations observed in the $A^1$ Π state were reanalysed and confronted with the previously known ones

Emission Spectroscopy of AlH: the X¹Σ⁺, A¹Π and C¹Σ⁺ States Characteristics

The visible spectrum of AlH has been investigated at high resolution between 20000 and 21500 $cm^{-1}$ using a conventional spectroscopic technique. The AlH molecules were formed and excited in an aluminium hollow-cathode lamp with two anodes, filled with a mixture of Ne carried gas and a trace of $NH_3$. The emission from the discharge was observed with a plane grating spectrograph and recorded by a photomultiplier tube. The 0-0 and 1-1 bands of the C¹Σ⁺-A¹Π system and 0-2 band of the A¹Π-X¹Σ⁺ were identified at 21126, 21368 and 20276 $cm^{-1}$, respectively. In total 121 transition wave numbers belonging to three bands were precisely measured (with accuracy of ±0.003 cm^{-1}) and rotationally analysed. The new data were elaborated with the help of recent X¹Σ⁺ state parameters reported by White et al. and of the C¹Σ⁺, A¹Π states constants reported by Szajna and Zachwieja. As a result of this merged analysis the set of the molecular parameters and rotational terms values for the three lower lying states of the AlH molecule have been significantly improved

Analysis of the A 1

This paper presents an attempt of examining the irregularities appearing in a complicated A$\text{}^{1}$Π state of the CH$\text{}^{+}$ molecule with their reasons provided. By using the experimental data for the A$\text{}^{1}$Π-X$\text{}^{1}$Σ$\text{}^{+}$ bands system of the $\text{}^{12}$CH$\text{}^{+}$ ion radical, it was proved that the vibrational and rotational quanta of the upper state reveal the same unusual behaviour, i.e. very clear nonlinear dependence on vibrational quantum number (v'≥3) of the upper state. Therefore, upper vibrational levels (v'≥3) of the A$\text{}^{1}$Π state cannot be determined by means of the equilibrium constants calculated in the previous works. Due to so far unidentified A$\text{}^{1}$Π state perturbations, the reduction of the wave numbers to the rovibronic parameters was carried out by means of individual, band-by-band analysis method, using with this end in view the nonlinear least squares method introduced by Curl and Dane, and Watson. This method allowed one to make already calculated constants of the rovibronic structure of regular lower state X$\text{}^{1}$Σ$\text{}^{+}$ of A-X system independent of possible perturbations appearing in the upper state of A$\text{}^{1}$Π of this system. It also enabled one to calculate for the first time the real (perturbed) term values for the A$\text{}^{1}$Π (v' =0, 1, 2, and 3) state of the $\text{}^{12}$CH$\text{}^{+}$ ion molecule. These values suggest that rotational irregularities in the A$\text{}^{1}$Π state examined are negligibly small. In order to confirm the nonexistence of rotational perturbations in the A$\text{}^{1}$Π (v' =0, 1, 2, and 3) state, up to the observed J$\text{}_{m}$ax level, appropriate graphs of functions f$\text{}_{x}$(J) and g$\text{}_{x}$(J) introduced by Gerö and Kovács, where x = Q, PR, and overline{PR}, were drawn. Also, their course was analysed in detail

Reanalysis of the Ångström System (B 1

The emission spectrum of the Ångström system $(B^1 Σ^{+} - A^1 \Pi)$ of $\text{}^{13}C^{16}O$ was obtained under high resolution with an accuracy estimated to be ± 0.002 $cm^{-1}$ as an emission spectrum using a high accuracy dispersive optical spectroscopy. The light source was a hollow-cathode lamp with two anodes built in our laboratory, with a previously deposited small quantity of $\text{}^{13}C$ carbon on the electrodes. The emission from the discharge was observed with a plane grating spectrograph and recorded by a photomultiplier tube. In total 195 transition wave numbers belonging to the strongest 0-1 and 0-2 bands of the B - A system were precisely measured. The modern rotational reanalysis made it possible to verify the molecular information for the both combining states of the Ångström system. In particular the rovibrational constants for the $B^1 Σ^{+}$ Rydberg state have been significantly improved ($B_0$ = 1.8625054(65) $cm^{-1}$ and $D_0=6.1384(52) \times 10^{-6} cm^{-1}$) and the obtained equilibrium rotational constants of this state are more accurate than known to date. Numerous rotational perturbations observed in the $A^1$ Π state were reanalysed and confronted with the previously known ones

Analysis of the A1\text{}^{1}Π State on the Basis of the Douglas-Herzberg Bands System in the CH+ Ion Molecule

This paper presents an attempt of examining the irregularities appearing in a complicated A$\text{}^{1}$Π state of the CH$\text{}^{+}$ molecule with their reasons provided. By using the experimental data for the A$\text{}^{1}$Π-X$\text{}^{1}$Σ$\text{}^{+}$ bands system of the $\text{}^{12}$CH$\text{}^{+}$ ion radical, it was proved that the vibrational and rotational quanta of the upper state reveal the same unusual behaviour, i.e. very clear nonlinear dependence on vibrational quantum number (v'≥3) of the upper state. Therefore, upper vibrational levels (v'≥3) of the A$\text{}^{1}$Π state cannot be determined by means of the equilibrium constants calculated in the previous works. Due to so far unidentified A$\text{}^{1}$Π state perturbations, the reduction of the wave numbers to the rovibronic parameters was carried out by means of individual, band-by-band analysis method, using with this end in view the nonlinear least squares method introduced by Curl and Dane, and Watson. This method allowed one to make already calculated constants of the rovibronic structure of regular lower state X$\text{}^{1}$Σ$\text{}^{+}$ of A-X system independent of possible perturbations appearing in the upper state of A$\text{}^{1}$Π of this system. It also enabled one to calculate for the first time the real (perturbed) term values for the A$\text{}^{1}$Π (v' =0, 1, 2, and 3) state of the $\text{}^{12}$CH$\text{}^{+}$ ion molecule. These values suggest that rotational irregularities in the A$\text{}^{1}$Π state examined are negligibly small. In order to confirm the nonexistence of rotational perturbations in the A$\text{}^{1}$Π (v' =0, 1, 2, and 3) state, up to the observed J$\text{}_{m}$ax level, appropriate graphs of functions f$\text{}_{x}$(J) and g$\text{}_{x}$(J) introduced by Gerö and Kovács, where x = Q, PR, and overline{PR}, were drawn. Also, their course was analysed in detail

New analysis of the Douglas-Herzberg system (A

Three bands of the A1Π- X1Σ+ system in the 12CH+ ion radical have been rephotographed under high resolution as an emission spectra using a Geissler-type discharge tube. The conventional technique of spectroscopy has been implemented. Using the Th lines as a standards, as well as an interferometric comparator equipped with a photoelectric scanning device, the 0-0 , 0-1 and 2-1 bands have been reanalyzed. By means of much longer bands (Jmax = 17 in the Q(J) branch of the 0-0 band; Jmax = 16 in the R(J) branch of the 0-1 band; Jmax = 14 in the P(J) and Q(J) branches of the 2-1 band), than have been observed so far, as well as the merged calculations, using another five bands given by Carrington et al. [A. Carrington, D.A. Ramsay, Phys. Scripta 25, 272 (1982)] additionally, more accurate molecular constants for the X1Σ+ state, the improved reduced band system origin Te = 24118.726 (14) cm-1 as well as for the first time the equilibrium molecular constants with their one standard deviation for the A1Π state in the CH+ molecule have been computed: ωe'=1864.402(22), ωexe'=115.832(14), ωeye'= 2.6301(24), Be'=11.88677(72), αe'= 0.9163(18), γe'= -2.29(12)×10-2, εe'= 4.95(20)×10-3, De'=1.92960(31)×10-3, βe'= 1.0733(50)×10-4, δe'= -1.312(16)×10-5, $\ q_e'= 4.102(23)\times10^{-2}$, αqe'= -3.14(16)×10-3, and qDe'= -2.20(14)×10-5 cm-1. Only in our research the addition to the zero-point energy Y'00=-1.9430 cm-1 and$Y''_{00}=1.8953$cm-1 have been calculated. The equilibrium bond lengths of r'e=1.235053(37) Å and$r''_e=1.1308843(30)$ Å for the A1Π and X1Σ+ states, respectively have been computed. Full quantum-mechanics characteristic of the A-X bands system in the 12CH+ molecule, i.e. RKR turning points, the Franck-Condon factors and r-centroids have been obtained. Dissociation energies DeX1 Σ+=(38470± 3503) cm-1 and DeA1 Π= (14415 ±3509)  cm-1 for the molecule under consideration have been estimated