Search

A robust and compact blue optical frequency reference within blue region was designed. A 40‐mW tellurium‐stabilized single‐frequency blue diode laser in external cavity was designed with an absorption spectroscopy method based on tellurium molecular transitions. Furthermore, the uncertainty of the frequency stabilization can be pushed to 2 × 10−9 at a 10‐s integration time. In addition, the correspondence frequency instability was 1.3 MHz when the laser wavelength was 445.75 nm. This study indicates that high‐stability frequency reference within the blue region can be achieved with an external cavity diode laser as opposed to the diode‐pumped frequency‐doubled solid‐state laser. [ABSTRACT FROM AUTHOR]

We designed a single‐frequency green laser system that can deliver a 60‐mW frequency‐tunable single‐longitudinal‐mode laser beam, having a 6.5 MHz linewidth at around 519 nm. An external cavity diode laser can provide a wavelength‐tunable single frequency laser beam, but its output power is limited. Therefore, an injection‐locked laser was designed with a Fabry–Perot type green InGaN laser diode in an external Littrow‐type cavity as the master laser and another laser diode of the same model as the slave laser. Injection locking can effectively enhance the output power and narrow the linewidth of the master laser. We found that the injection locking occurred at longitudinal mode matching between the master laser and slave laser diodes, which is located at a specific frequency for a periodical applied current. The side peaks of the injection locking due to the transverse mode mismatching were recorded and analyzed. [ABSTRACT FROM AUTHOR]

The 2 1Π state of NaH has been observed up to the last bound vibrational level using pulsed optical-optical double resonance fluorescence depletion spectroscopy. A total of 20 rovibrational energy levels (v = 2–4 and J = 1–9) were assigned to this electronic state by means of comparing the successive rovibrational spectra to the eigenvalues of the ab initio potential energy curve. The decrease of background fluorescence near the atomic asymptotic limit Na(3d) + H(1s) is an indication of reaching the dissociation limit of the NaH 2 1Π state. Unobserved rovibrational levels (v = 0 and 1) are due to poor Franck-Condon overlap of 2 1Π ← A1Σ+ transition within the accessible rovibrational levels of intermediate A1Σ+ state of this work. [ABSTRACT FROM AUTHOR]

The nd 1Δg (n=6, 7, and 8) Rydberg states of Na2 correlating with the asymptotic limits of Na(3s)+Na(nd) have been observed using high-resolution cw optical-optical double resonance spectroscopy corresponding to the rovibrational transitions X 1Σg+(v″,J″)+hνpump→B 1Πu(v′,J′)+hνprobe→nd 1Δg(v,J). Totals of 104, 83, and 45 identified rovibrational e/f-parity levels in the ranges of v=0–11, 11≤J≤83; v=0–10, 11≤J≤83; and v=0–10, 11≤J≤65, have been assigned to the 6d 1Δg, 7d 1Δg, and 8d 1Δg states, respectively. Using the observed quantum levels, molecular constants were determined from the Dunham fits of the e-parity levels and the Rydberg–Klein–Rees potential curves were constructed for the nd 1Δg(n=6–8) states. The characteristics of the estimated Λ-doubling splitting constants (q0, qv, and μ) with n(=5–8) of the nd 1Δg series have been explored. Detailed investigations reveal that the nd 1Δg(n=6–8) states involve L uncoupling from the internuclear axis and each of these states is affected by an asymmetric perturbation caused by the up and down adjacent states. The rotational-branch intensity and position anomalies in the observed spectra of the nd 1Δg series (n=5–8) of Na2 lead to the conclusion that due to the effects of the L-uncoupling perturbations, the same l complexes approaching the same ion-core limits result in the same l-mixing processes which lead to the formation of the supercomplexes due to the anisotropy of the molecular-ion [Na2+(3s)] field. This would open up opportunities to study the effects of L uncoupling and perturbations in the nd series and high Rydberg states of other alkali dimers. [ABSTRACT FROM AUTHOR]

The 1 3Δg state of Na2 has been studied extensively by both filtered fluorescence and ionization detection and analyzed by both Dunham-type expansion and near-dissociation expansion (NDE) models in the analysis. Our observations have covered 99.998% of the potential well depth with the outermost Rydberg–Klein–Rees (RKR) turning point at 28.02 Å. NDE analysis gives Te=28 032.468 (±0.021) cm-1, De=7162.436 (±0.021) cm-1, and Re=3.463 81 (±0.000 28) Å. Significant long-range behavior in the near dissociation levels has been observed. Fitting of the RKR turning points gives the long-range coefficients C5=1.388 (±0.031)×106 cm-1 Å5 and C6=0.4008 (±0.0046)×108 cm-1 Å6. These newly observed results show reasonable agreement with recent theoretical calculations. © 1995 American Institute of Physics. [ABSTRACT FROM AUTHOR]

This paper critically surveys the best available spectroscopic data for the two lowest electronic states (X 1Σ+g and a 3Σ+u) of K2. Since both states are known up to dissociation, they can be used to determine Coulomb and exchange contributions to the intermediate and long range interaction potentials. The multipolar expansion representation of the Coulomb (dispersion) energy at long range (-ΣnCnR-n) and the exponential representation of the exchange energy (Ae-αR) as well as a variety of theoretical calculations are compared with these empirical results. Finally, dissociation energy values are discussed and improved dissociation energies for the X 1Σ+g (De=4449.1±1.0 cm-1) and the a 3Σ+u state (De=252.9±1.1 cm-1) proposed. © 1994 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The 4 1Σ+g ‘‘shelf’’ state of Na2 was extensively investigated using optical–optical double resonance spectroscopy and an ultrasensitive ionization detector. A total of 179 vibrational levels-(0≤v≤127 are from previous work by using filter-photomultiplier tube fluorescence detection) were observed in this state, which covered more than 99.8% of the well depth. The Rydberg–Klein–Rees (RKR) potential energy curve was constructed with maximum outer turning point R178+ = 17.60 Å. The comparison of the long range portion of the RKR potential energy curve and the potential curve calculated from V(R)=ΣnCn/Rn is discussed. Avoided crossings around the shelf with the 3 1Σ+g state and near dissociation with the 5 1Σ+g state are also discussed. [ABSTRACT FROM AUTHOR]

Using optical–optical double resonance and an ultrasensitive ionization detector, we have been able to extensively study a wide range of internuclear distances for the 5 1Σ+g state of Na2. Using a combination of spectroscopic data and the ab initio calculations, we have constructed a hybrid potential which has an outer well at shelf region. For this hybrid potential, there are 54 vibrational levels in the inner well (which all have been observed in this work) and 12 vibrational levels in the outer well (of which only the last level has been observed in this work). Above the potential barrier, 78 additional vibrational levels have been observed in this work. These spectroscopic data represent about 99.8% of the potential well depth. [ABSTRACT FROM AUTHOR]

The 3 1Σ+g state of Na2 has been extensively studied using an optical–optical double resonance technique and a shielded cylindrical space-charge-limited ionization detector. A wide range of vibrational quantum numbers 0≤v≤141 was observed which covered over 99.9% of the potential well depth. A ‘‘shelf’’ on the potential energy curve was found near v=23. A hybrid potential was constructed based on the Rydberg–Klein–Rees (RKR) potential curve and a local inverse perturbation approach (IPA) for the shelf region. For this potential, there is a shallow second local minimum ∼5 cm-1 in depth at the shelf region. The long range energy also compares well with long range theory. [ABSTRACT FROM AUTHOR]

All quasibound vibrational energy levels v=27 and 28 of the Na2 3 1Πg state were accessed by using optical–optical double resonance and detected with a shielded ionization detector. The line broadening due to the tunneling effect was observed to be larger than 1 cm-1 at the rovibrational level v=28, J=31. The potential curve has been determined by the Rydberg–Klein–Rees method and modified using Jeung’s calculation for the large distance barrier and comparison of the calculated and the measured line widths. The barrier height was found to be ∼126 cm-1 above its asymptotic limit (3s+4p) at 5.98 Å. There also exists an unobserved shallow outer well with depth ∼35 cm-1 at 9.5 Å according to our modification of Jeung’s calculated potential. One way to possibly probe this outer well is also discussed. [ABSTRACT FROM AUTHOR]