Excited Electronic States of Sr2: Ab Initio Predictions and Experimental Observation of the 21Σu+ State.

Despite its apparently simple nature with four valence electrons, the strontium dimer constitutes a challenge for modern electronic structure theory. Here we focus on excited electronic states of Sr2, which we investigate theoretically up to 25000 cm-1 above the ground state, to guide and explain new spectroscopic measurements. In particular, we focus on potential energy curves for the 11Σu+, 21Σu+, 11Πu, 21Πu, and 11Δu states computed using several variants of ab initio coupled-cluster and configuration-interaction methods to benchmark them. In addition, a new experimental study of the excited 21Σu+ state using polarization labeling spectroscopy is presented, which extends knowledge of this state to high vibrational levels, where perturbation by higher electronic states is observed. The available experimental observations are compared with the theoretical predictions and help to assess the accuracy and limitations of employed theoretical models. The present results pave the way for future more accurate theoretical and experimental spectroscopic studies.

The C(2)1Πu state in Rb2. Observation and deperturbation.

We report a systematic study of the C(2)1Πuelectronic state in rubidium dimer, observed in polarization labelling spectroscopy experiment through the C ← X1Σg+ transitions recorded under rotational resolution in two isotopologues 85Rb2 and 85Rb87Rb. Regularity of the vibrational progressions was distorted by numerous interactions with the surrounding 21Σu+, 23Πuand 33Σu+states. Deperturbation was performed by coupled-channels analysis taking into account spin-orbit and rotational interactions. Potential energy curves and parameters describing the off-diagonal matrix elements were determined as functions of internuclear distance. About 3000 line frequencies from the present study are reproduced with a standard deviation of 0.07 cm-1, in agreement with the experimental accuracy. Along with this, the model is consistent with all high resolution experimental data on the involved electronic states, available in the literature.

On the 31Πu state in caesium dimer.

Polarisation labelling spectroscopy technique was employed to study the 31Πu state of Cs2 molecule. The main equlibrium constants are Te=20684.56cm-1,ωe=30.62 cm-1 and Re=5.27 Å. Vibrational levels v=4-35 of the 31Πu state were found to be subject to strong perturbations by the neighbouring electronic states. Energies of 3352 rovibronic levels of the perturbed complex were determined.

Determination of the C(3)1Σ+ state potential energy curve in KCs molecule based on polarisation labelling spectroscopy data.

The C(3)1Σ+ state of KCs molecule was studied experimentally employing the polarisation labelling spectroscopy (PLS) technique. The experiment extended the prior knowledge of the state adding more than 40 vibrational levels to the previously existing data. A pointwise potential energy curve was constructed for the investigated state with the inverted perturbation approach (IPA) method, basing on experimentally determined energies of over 1300 rovibrational levels.

The RbSr 2Σ+ ground state investigated via spectroscopy of hot and ultracold molecules.

We report on spectroscopic studies of hot and ultracold RbSr molecules, and combine the results in an analysis that allows us to fit a potential energy curve (PEC) for the X(1)2Σ+ ground state bridging the short-to-long-range domains. The ultracold RbSr molecules are created in a µK sample of Rb and Sr atoms and probed by two-colour photoassociation spectroscopy. The data yield the long-range dispersion coefficients C6 and C8, along with the total number of supported bound levels. The hot RbSr molecules are created in a 1000 K gas mixture of Rb and Sr in a heat-pipe oven and probed by thermoluminescence and laser-induced fluorescence spectroscopy. We compare the hot molecule data with spectra we simulated using previously published PECs determined by three different ab initio theoretical methods. We identify several band heads corresponding to radiative decay from the B(2)2Σ+ state to the deepest bound levels of X(1)2Σ+. We determine a mass-scaled high-precision model for X(1)2Σ+ by fitting all data using a single fit procedure. The corresponding PEC is consistent with all data, thus spanning short-to-long internuclear distances and bridging an energy gap of about 75% of the potential well depth, still uncharted by any experiment. We benchmark previous ab initio PECs against our results, and give the PEC fit parameters for both X(1)2Σ+ and B(2)2Σ+ states. As first outcomes of our analysis, we calculate the s-wave scattering properties for all stable isotopic combinations and corroborate the locations of Fano-Feshbach resonances between alkali Rb and closed-shell Sr atoms recently observed [V. Barbéet al., Nat. Phys., 2018, 14, 881]. These results and more generally our strategy should greatly contribute to the generation of ultracold alkali-alkaline-earth dimers, whose applications range from quantum simulation to state-controlled quantum chemistry.

High-lying electronic states of the rubidium dimer-Ab initio predictions and experimental observation of the 5(1)Σu(+) and 5(1)Πu states of Rb2 by polarization labelling spectroscopy.

Two-colour polarization labelling experiments have been used to explore the excitation spectrum of the rubidium dimer in the region 25,500-27,000 cm(-1), probing two mutually interacting states, identified from ab initio calculations as the 5(1)Σu(+) and 5(1)Πu states whose atomic dissociation products are Rb(5s) + Rb(5d). Treating the rather irregular progressions observed in the excitation spectra as transitions to single states with (numerous) local perturbations, we propose spectroscopic parameters and potential energy curves to describe the investigated levels. Observations cover more than 20 vibrational levels in the inner minima of both the 5(1)Πu and 5(1)Σu(+) states. Analysis was guided by ab initio calculations performed to describe the (1,3)Λg,u electronic states of Rb2 up to the Rb(5s) + Rb(5f) atomic asymptote. The theoretical potential energy curves are given in ASCII format in an electronic supplement to this paper.

[Usefulness of width and amplitude of P wave for prognosis of the efficacy of atrial sensing in patients with an implanted VDD pacemaker]. / Przydatnosc czasu trwania i amplitudy zalamka P w przewidywaniu skutecznosci sterowania przedsionkowego u chorych z implantowanym rozrusznikem VDD.

UNLABELLED: VDD stimulation is accepted as alternative mode of cardiac pacing to DDD in patients with atrio-ventricular (AV) conduction block and preserved sinus node function (SA). AIM OF THE STUDY: An attempt has been made to determine the relationship between width and amplitude of the P wave obtained during assessment the patient for the implantation procedure and the effectiveness of AV synchronization (PAS). MATERIAL AND METHODS: The study involved a group of 65 patients (43 male, 22 female), aged 66.6 +/- 12.7 with clinically significant disturbances of AV conduction, who did not reveal symptoms of concomitant disturbance in SA node automaticity. The width and amplitude of the P wave of the surface ECG were studied prior to the implantation procedure. Follow-up was carried out 3-4 days and 1, 3, 6 and 12 months after the procedure. The effectiveness of PAS was estimated by event counter read-out. RESULTS: Over the 12-month follow-up, the average value of the PAS coefficient was 95% for the entire group of patients. In 74% (subgroup A) synchronization was highly effective (PAS > or = 95%); in the remaining 26% (subgroup B) PAS occasionally fell below 95%. A statistically significant correlation between the width of the P wave of the surface ECG and the effectiveness of PAS was clearly demonstrated. In subgroup B, P wave was longer than in subgroup A (105 +/- 16 vs. 94 +/- 14 ms; p < 0.005). The width of P wave above 100 ms was the cutoff value of the ROC curve predicting PAS < 95%. CONCLUSIONS: The width of P wave obtained from surface ECG is correlated with effective AV synchronization. The value above 100 ms was predisposed to atrial undersensing.

Usefulness of electrocardiographic and echocardiographic parameters for predicting the efficacy of atrioventricular synchronisation during a single lead VDD/R pacing.

BACKGROUND: The VDD/R pacing is accepted as an alternative to DDD/R pacing in patients with atrioventricular conduction block (AVB) and intact sinus node function. AIM: To determine the relationship between parameters obtained during assessment of the patient for the implantation procedure, using electrocardiographic (ECG) and echocardiographic (ECHO) data, and the effectiveness of AV synchronisation. METHODS: The study involved a group of 65 patients (43 males, 22 females), aged 66.6 + 12.7 with clinically significant disturbances of AV conduction, who did not reveal symptoms of concomitant abnormalities in sinus node automaticity. Selected ECG and ECHO parameters were studied prior to the implantation procedure. Repeat examinations were done at 3-4 days and at 1, 3, 6 and 12 months after the procedure. The effectiveness of AV synchronisation (PAS) has been estimated by event counter read-out and ECG Holter monitoring. RESULTS: In 74% patients (subgroup A) synchronisation was highly effective (PAS _ 95%); in the remaining 26% subjects (subgroup B) PAS occasionally fell below 95%. In subgroup B, the P wave was longer than that in subgroup A (105 +/- 16 vs. 92 _ 13 ms; p < 0.05). The dimensions of the right and left heart chambers were greater in subgroup B. Patients in subgroup B had lower ejection fraction (49.4 +/- 13.7% in B vs. 58.2 +/- 11.3% in A) and revealed symptoms of heart failure. The following cut-off values for each echocardiographic and electrocardiographic parameter predisposing to PAS < 95% during VDD/R pacing ('undersensing') were identified: RVEDd > 26 mm, RVESd > 24 mm, LVEDd > 59 mm, LVESd > 37.3 mm, APD LA > 44 mm, SID RA > 52 mm, LMD RA > 48 mm, RAvol> 54 ml, RAarea > 19 cm2, SID LA > 57 mm, LMD LA > 46 mm, EF < 52%, P wave width > 100 ms. Significant predictors of PAS < 95% in the univariate analysis were RVEDd, RVESd, LVEDd, LMD RA, SID RA, RAvol, RAarea, EF, and in the multivariate analysis RVEDd, RVESd, LMD RA, RAarea, EF. CONCLUSIONS: Selected parameters obtained from ECG (P wave width) and echo examinations are correlated with effective AV synchronisation. Enlargement of the right and left heart chambers (atrial, ventricular), reduction of the ejection fraction and congestive heart failure are associated with impaired AV synchronisation in VDD/R pacemakers. In multivariate analysis, only the higher dimensions of the right ventricle and atrium and the lower ejection fraction of the left ventricle were significantly associated with the PAS < 95%.

[The influence of radiofrequency (RF) ablation of the atrioventricular junction in atrial fibrillation on left ventricular systolic function, exercise tolerance and quality of life]. / Wplyw leczenia migotania przedsionków metoda przezskórnej ablacji RF lacza przedsionkowo-komorowego na wybrane parametry czynnosci skurczowej miesnia lewej komory, wydolnosc wysilkowa i jakosc zycia chorych.

UNLABELLED: In patients with drug refractory atrial fibrillation radiofrequency (RF), ablation of the atrioventricular (AV) junction and pacemaker implantation is an alternative procedure. The aim of this study was to assess the left ventricular systolic function, exercise tolerance and quality of life (QOL) in patients who underwent RF AV junction ablation and permanent pacemaker implantation. MATERIAL AND METHODS: 24 patients (14 male, 10 female, 64.8 +/- 11.0 years) underwent RF ablation. The duration of symptoms was 4 +/- 1.9 years prior to ablation. Post ablation, the selected pacing mode was DDDR for the 4 patients with paroxysmal AF and VVIR for the 20 patients with chronic AF. The underlying heart disease was coronary artery disease (17 CAD), arterial hypertension (15 AH) and heart failure (9 HF). Prior to the ablation and after 6 months follow-up--an ECHO, exercise tolerance (the six minute walk -M6) and QOL assessment (the questionnaire of SF-36, functional symptomatology scale, DASI scale) were performed. The NYHA class was also evaluated. RESULTS: The patients showed a significant improvement in NYHA class (p < 0.005), in QOL (SF-36, p < 0.0025; symptomatic score, p < 0.025; DASI, p < 0.01) and in the M6 (p < 0.01). We did not find significant changes in left ventricular performance. The significant correlation was observed between the SF-36 and functional symptomatology (r = 0.71) and DASI (r = 0.53). We divided our patients into two groups: Group A (patients with the higher NYHA class, p < 0.025) with significant improvement QOL and Group B with insignificant improvement of QOL. Post ablation in group A we--observed significant improvement in NYHA class and M6 (p < 0.01). CONCLUSIONS: 1. In patients with drug refractory atrial fibrillation, RF AV junction ablation and permanent pacemaker implantation significantly improve the QOL, M6 and NYHA class. 2. Significant improvement of QOL as well as in M6 can be expected after RF ablation with pacemaker implantation, especially in patients with more advanced hart failure (higher NYHA class).

[Dynamic of the changes of the paced QT dispersion after ventricular pacemaker implantation (WIR) and radiofrequency atrioventricular junction ablation in drug refractory atrial fibrillation]. / Dynamika zmian dyspersji odstepu QT po implantacji rozrusznika komorowego VVIR z nastepowa ablacja metoda RF lacza przedsionkowo-komorowego w opornym na farmakoterapie migotaniu przedsionków.

INTRODUCTION: Transcutaneous RF catheter ablation of the atrioventricular junction (AVJ) in pts with ventricular pacemaker (VVIR) implantated is an accepted treatment for drug-intolerant or drug refractory atrial fibrillation. The ventricular arrhythmias and sudden cardiac death may be associated with increased of QT dispersion (QTD), mainly in pts with reduced LV function (low ejection fraction - EF) after AVJ ablation. The present study evaluates the dynamic of the changes of QTD in response to a sudden pacing rate drop from 80/min to 40/min in follow up 1 day, 3, 6 and 9 months after ablation (1d, 3m, 6m, 9m). MATERIAL AND METHODS: The 12-lead ECGs were recorded on 22 pts (mean age 72.6+/-5.4 yrs) (10 with low EF (<50%) - group A, 12 with normal EF (> or =50%) - group B) on the 1 day, 3, 6 and 9 months following AVJ ablation during a sudden drop in ventricular pacing rate from 80 to 40 beats/min. The maximum QT interval (QTM), minimum QT interval (QTm), and QTD were measured on the last 5 beats prior to the rate drop (QTM-80, QTm-80, QTD-80) and on the first 5 beats after the rate drop (QTM-40, QTm-40, QTD-40). These QT parameters were compared. The echocardiographical studies were performed on the 1d, 3m, 6m and 9m following AVJ ablation. RESULTS: In response to a sudden paced heart rates drop from 80 to 40 beats/min, the DeltaQTM (QTM-40 - QTM-80) increased during follow-up in both groups, while the DeltaQTm (QTm-40-QTm-80) increased in group B(23.3+/-25.7 in 1d, 27,5+/-20.1ms in 9m; p< 0.001), but not in group A (1+/-16.6 in 1d, 5+/-25.1ms in 9m). Consequently, the AQTD (QTD-40 - QTD-80) increased significantly in group A at 6 months (29+/-31.1ms; p<0.05) but not in group B (9.2+/-17.3msl. The negative correlation between QTD-40, QTD-80 and EF was observed in group A. CONCLUSIONS: Following AVJ ablation, QTD increased during a sudden rate drop in pts with reduced LV function, but not in pts with EF > or = 50%. The significant correlation between QTD and paced rate was found in pts with LV dysfunction. The increased QTD in response to a sudden heart rate drop in pts with low EF was due to a failure of the expected prolongation of the QTm.

Biochemical markers of myocardial damage after radiofrequency ablation.

BACKGROUND: Radiofrequency catheter ablation (RFCA) may cause myocardial injury. AIM: To assess changes in myocardial enzymes levels following RFCA. METHODS: Creatine kinase (CK), CK-MB, aspartate aminotransferase (GOT), alanine aminotransferase (GPT), troponin I and myoglobin levels were assessed in 53 patients (33 females, 20 males, mean age 53 years, range 23-78 years) before and 20 hours after successful RFCA (WPW type A = 13, WPW type B = 10, atrio-ventricular nodal tachycardia n = 17, atrial fibrillation or flutter n = 5, atrial tachycardia n = 2 and complex arrhythmias n = 6). RESULTS: The mean number of RF applications was 10.4, cumulative energy - 22 671 J, duration of application - 468 sec, and temperature - 58 degrees C. A significant post-RFCA increase in the troponin I and myoglobin levels was found whereas the changes in CK and GOT levels were less pronounced. A significant correlation between troponin I elevation and RFCA energy, particularly in males, was documented. There was a trend towards a decrease in the GPT and CK-MB levels. Troponin I and myoglobin levels increased regardless of the site of RF energy application. CONCLUSIONS: Troponin I and myoglobin are useful for the assessment of RFCA-induced myocardial injury, regardless of the site of RFCA application.

[Long-term results of radiofrequency (RF) catheter ablation of cardiac arrhythmias]. / Odlegla skutecznosc zabiegów przezskórnej ablacji RF w leczeniu zaburzen rytmu serca--doswiadczenia wlasne.

BACKGROUND: Although the short-term results after radiofrequency (RF) catheter ablation of atrioventricular nodal reentrant tachycardia (AVNRT), accessorry pathway (AP), atrioventricular junction (AVJ) and common atrial flutter (Aflu) have been widely reported, there is insufficient data on long-term outcome. AIM: To evaluate the long-term efficacy of RF ablation of cardiac arrhythmias in a single center. METHODS: The study population consisted of 349 consecutive patients (mean age 49.5 years) who underwent RF ablation of AP (136 patients), AVNRT (105 patients), AVJ (86 patients) or Aflu (15 patients). In 4 patients two AP and in 3 patients AP and AVNRT were ablated during the same session. The patients were subsequently followed-up for an average of 44.3 months (12-76 months). RESULTS: Ablation was successful in 341 patients (97.7%). Major complications occurred in 8 patients (2.3%) and included av block (6 patients), ventricular fibrillation (1 patient) and cardiac tamponade (1 patient). Tachycardia recurrences were observed in 21 patients (6.2%) after successful ablation. All the recurrences occurred within 10 months (mean 2.3 months) after ablation. The recurrence rate was 5.8% (6 patients) in the AVNRT group, 9.2% (12 patients) in the AP group, 1.2% in the AVJ group (1 patient) and 13% (2 patients) in the Aflu group. The differences between groups were insignifficant. CONCLUSIONS: (1) The immediate success rate of RF ablation of AVNRT, AP, AVJ or Aflu was high and there was a low incidence of complications. (2) The recurrence rate during long-term observation is low. (3). All the recurrences occurred within 10 months after successful ablation.