Opto-acoustic spectroscopy with a visible CW dye laser

The first use of a tunable visible laser in conjunction with an opto-acoustic cell is described. By using a longitudinal resonance of the gas cell NO₂ can be detected around 10 p.p.b., the same order of detectivity as in the infrared. The use of the technique for studying photodissociation in the visible and u.v. is discussed.     

Direct absorption spectroscopy using a rapidly tunable CW dye laser

Using a recently developed electronically tunable cw dye laser, the spectrum of an absorption sample could be obtained and repeatedly scanned every 10 μsec. The system is potentially capable of monitoring spectral changes in times as short as 10^?7 sec.     

High resolution laser induced fluorescence excitation spectroscopy of jet-cooled terrylene

High resolution laser induced fluorescence excitation spectra upon absorption in the A¹B_3u ← X¹A_g band of jet-cooled terrylene have been recorded. Precise energies of three vibronic transitions are deduced. Low lying vibrations are found in both electronic states. Rotational constants in ground and excited state are determined by band contour analysis. Terrylene is a medium-size polycyclic aromatic hydrocarbon (PAH) and a possible carrier of diffuse interstellar bands (DIB). The results of the jet experiments are discussed regarding the PAH-DIB hypothesis.     

High resolution laser fluorescence spectroscopy in the deep blue spectral region

High-resolution laser spectroscopy measurements have been performed in the wavelength region around 4000 Å using a pulsed dye laser acting on a collimated atomic beam. Extra-cavity Fabry-Pérot filtering was used to achieve a narrow line-width of the laser light. Isotope shifts were measured in the 4216 Å and 4202 Å rubidium lines with the result Δσ(87, 85)=124.3(4)MHz, andΔσ(87, 85) = 124.2(7)MHz, respectively, and in the 3988 Å ytterbium line with the resultδσ(176, 174)=?509(4)MHz, Δσ(174, 172)=?530(4) MHz.     

Picosecond fluorescence studies by intracavity gain spectroscopy in a modelocked dye laser

This article presents measurements which combine modelocking technique with intracavity spectroscopy. To test this approach, a sample (10^–5 m ethanolic solution of 1,4-dihydroxyanthranquinone) was inserted in a modelocked Ar⁺ ion laser and probed by intracavity pulses of a synchronously pumped dye laser. The probing of the sample results in an amplification of the dye laser output. Maximum output was measured if the pulses of the dye laser temporally overlapped with those of the Ar⁺ ion laser inside the sample. Under this condition, the spectral laser intensity was shaped by the spectrum of stimulated fluorescence which originated from a molecular vibronic state populated by pump laser excitation.Presented at LASERION '91, June 12–14, 1991, München (Germany)     

A megawatt dye laser oscillator-amplifier system for high resolution spectroscopy

Peak powers in excess of 4 MW in the visible and 1.3 MW in the UV with linewidths as narrow as 80 MHz are generated with three YAG pumped amplifier stages following a cw dye oscillator. The laser pulses are nearly Fourier transform limited in frequency space and diffraction limited in coordinate space.     

Raman spectroscopy in a CW chemical laser

Spatially-resolved measurements of specie concentrations and temperature are important in obtaining an understanding of the fluid-mechanical, optical, and chemical processes occurring in chemical lasers. This understanding may lead to direct improvements in laser operation and to improved modeling capability. Presently, such detailed data for an actual laser are not available.Spontaneous Raman spectroscopy is a powerful species diagnostic because the Raman-scattered frequencies are unique to the particular scattering specie. In addition, the strength of the scattering is directly proportional to the concentration of the scatterer, and the signal is not quenched by atomic or molecular collision. However, the spontaneous Raman effect is very weak, thus requiring a strong excitation source and sensitive detection methods in order to obtain useful signals.A 15-watt argon-ion laser operating at 488.0 or 514.5 nm was used to excite Raman spectra of the major species in an actual-scale, cw, supersonic, HF/DF chemical laser. From these measured spectra, spatially-resolved and time-averaged specie concentrations and rotational temperatures were determined. These results are presented and compared to theoretical predictions. Observations of flow nonuniformities and fluid-mechanical structures are also discussed.     

High resolution laser spectroscopy of Ba Rydberg atoms

The purpose of the present paper is to illustrate some selected aspects of high resolution laser spectroscopy of Rydberg atoms, rather than giving an extensive review of the state of the art. The following topics will be discussed: (i) Excitation and detection of Ba Rydberg atoms with principal quantum numbers up ton≲300; (ii) Stark effect and atomic diamagnetism of high-n Ba Rydberg states in thel-mixing region, (iii) Resonance in singlet-triplet mixing of 6snp¹P₁ and 6snd¹D₂ Ba Rydberg states deduced from hyperfine structure measurements.     

High resolution laser excitation spectroscopy of barium monosulfide

High-resolution spectra of BaS were recorded using laser excitation spectroscopy. BaS molecules were synthesized in a Broida-type oven. The observed rotationally-resolved spectrum of BaS in the 12 100–12 765 cm^?1 spectral range contains the 2-1, 3-1, 3-2, 4-2, 5-2, 5-3 vibrational bands of the A′¹Π–X¹Σ⁺ transition and the 4-1, 5-1, 5-2 vibrational bands of the a³Π₁–X¹Σ⁺ transition. Approximately 1000 lines of the A′¹Π–X¹Σ⁺ transition and 600 lines of the a³Π₁–X¹Σ⁺ transition for the main isotopologue ¹³⁸Ba³²S (67.5% natural abundance) were measured. Rotational and vibrational parameters were derived for the A′¹Π and a³Π₁ states.     

An investigation of laser-induced fluorescence for measuring velocity distributions of neutral atoms using a CW dye laser

The velocity distribution of evaporated Zr atoms has been measured by means of laser-induced fluorescence using a cw dye laser by scanning the laser line across the Doppler-broadened absorption line profile of the atoms. It is shown that the experimental data can be explained on the basis of an excitation theory for a three-level system developed from basic principles. It was calculated that the probability for an atom to be in the excited state mainly depends on the radiation-power density of the laser and on the residence time of the atom in the exciting laser light. It was found that the laser frequency must be well stabilized in order to meet the assumptions in the excitation calculation. Otherwise deviations to the theoretical predictions appear in the experimental results due to the jitter of the dye laser.     

A frequency stabilized,cw dye laser for high resolution spectroscopy

A single frequency, jet stream cw dye laser spectrometer locked to a stable high finesse optical reference cavity is described. This system is capable of maintaining a frequency stability of ± 1 MHz/min and a continuous scan of up to 6 GHz.     

CW dye laser emission beyond 1000 nm

We report CW dye laser emission extending the spectral range up to 1020 nm with three carbocyanines. These dyes are pumped by the infra-red lines of a krypton laser. They have a fairly good stability in time. 50 mwatt tuned output power has been obtained at 1000 nm.     

Saturated absorption experiments using a free running CW dye laser

The hyperfine structure of some new iodine lines has been observed over the tuning range of Rhodamine 6G (5800–6200 Å), using a free running, single mode cw dye laser. The resolution obtained in this experiment allowed to calculate the hyperfine constants of the excited state (³π₀⁺) of iodine with an accuracy of 2% for the quadrupole coupling constant and 50% for the magnetic one.     

A mirror-free cavity configuration for a CW ring dye laser

A new cavity configuration without mirrors is described for a CW ring dye laser. The cavity design is based on a new type of focusing prism which uses the Brewster angle of incidence and total internal reflection. Special roof prisms allow wavelength tuning. All of these elements are made from uncoated quartz thus allowing dye laser operation over a large range of wavelengths. CW operation as well as synchronously pumped mode locked operation with intracavity doubling is reported using the Rhodamine 6G dye.     

连续波环形染料激光器的单向运转特性

本文讨论了连续波环形染料激光器的单向运转特性。采用改进的Ganiel速率方程模型,分析了在单向运转条件下泵浦光通量、染料分子密度等参量对激光光通量、激发单重态粒子集居数密度以及增益的影响;揭示了在连续波环形染料激光器中单向运转条件下存在粒子集居数密度的非对称性、激光光通量与激活介质内空间位置的相关性和增益峰值波长的扫描现象。本文给出了数值计算结果。     

Powerful dye laser oscillator-amplifier system for high resolution and coherent pulse spectroscopy

A peak power output of 100 kW in the visible at a linewidth as low as 60 MHz has been generated by using a cw dye laser oscillator followed by three single pass dye amplifier stages (or one double pass stage and one single pass stage), pumped by a single 1 MW nitrogen laser. The very high output power obtained in this laser system may be used to produce coherent ultraviolet pulses by sum or second harmonic generation in non-linear crystals or by third order mixing in atomic vapor.     

Design of a dye laser for nonlinear spectroscopy

Special requirements should be met by a pulsed dye laser in order to provide reproducible data in a nonlinear experiment. The cavity and pumping laser are chosen to minimize effects due to detailed dye characteristics. A suitable ruby pumping laser is described.     

Non-linear fluorescence in dye solutions induced by a low power laser

Measurements of the fluorescence intensity I_F, excited by two-photon pumping, have been carried out in different dye solutions by utilizing a low power cw laser (I_L ≈ 12 mW) and a particular experimental technique. A considerable departure from the quadratic law I_F ∝ I²_L with the varying of 2hω - ΔE_i quantity has been detected. This behaviour has bee n accounted for by considering the dependence of the non-linear and linear cross sections relative to the S₀ → S₁ and S₀ → S₂ transitions on the laser frequency.     

An alternate model of CW dye laser intracavity absorption

A new model is presented for intracavity absorption in a CW multimode dye laser based on the similarity between the laser and a self-quenched super- regenerative oscillator. The model suggest that the primary interaction mechanism between the atomic absorber and the laser is through a modification of the background radiation level from which the oscillation builds up. Numerical calculations are carried out leading to a prediction of the spectral line shape to be observed in intracavity absorption as well as the dependence of the signal on absorber density and pump power.     

Feedback controlled self-excitation of optical pulses in a CW dye ring laser

Feedback controlled self-excitation of optical pulses of nanosecond duration has been observed to occur rather reliably in a CW dye ring laser, oscillating in a traveling mode. These observations are described analytically by means of a direct time domain approach. It is shown that a steady-state Gaussian pulse whose time duration determined from the self consistency condition in terms of system characteristics describes accurately the observed pulse behaviors. Supported in part by a NSF Grant.