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1.
Summary The optogalvanic signal (OGS) induced in a uranium-neon hollow-cathode discharge was measured as a function of the laser power
density for the 0→16900 cm−1 (591.5 nm) uranium transition. Theoretical relations derived by solving a two-level system rate equations showed the OGS
dependence on the laser photon flux, for a modulated c.w. light and for stimulated transitions starting from the ground state.
A fitting of the theoretical relations to the experimental measurements allowed the determination of the σ0 τ product, that is, the saturation parameter of the transition. The results showed good agreement between the σ0 τ values obtained by the optogalvanic and the usual optical absorption processes. 相似文献
2.
Vas Dev M. L. Shah A. K. Pulhani B. M. Suri 《Applied physics. B, Lasers and optics》2005,80(4-5):587-594
A U–Ne hollow cathode discharge tube is used as a source of uranium atomic vapors as well as a photoelectron/photoion detector
for carrying out two-color three-photon photoionization spectroscopy of uranium. Using the uranium excitation transition 0
cm−1 (5L
6
0
) → 16 900.38 cm−1 (7M7) at 591.5-nm laser wavelength as a first step transition and scanning the wavelength of a second laser from 558 to 568 nm,
high-lying odd-parity atomic levels of uranium are studied in the energy region 34 500–34 813 cm−1. All the expected 21 odd-parity atomic levels identified by various researchers in this region are observed in a single spectrum,
demonstrating the high sensitivity achieved therein. In addition to this, we have identified eight autoionization resonances
of uranium starting from its odd-parity atomic level at 33 801.06 cm−1 pumped by two-photon excitation. Four out of these eight autoionization resonances are observed for the first time. 相似文献
3.
The most recently measured differential cross-section data forπ
−
p → η’n has been fitted by using a simple Regge pole model with phenomenological residue functions. It has also been observed that
this inelastic process has the scaling property. 相似文献
4.
《Applied physics. B, Lasers and optics》1981,24(1):33-38
We report infrared laser emission in the region of 3 to 5 μm from sodium vapour optically pumped by a pulsed dye laser with
wavelengths ranging from 585 to 610nm. Twophoton excitation processes are believed to be responsible for the primary excitation.
Both molecular transitions (4 to 5 μm) between high lying states, and atomic transitions (52
S
1/2−42
P
3/2,1/2 at 3.41 μm) have been identified. 相似文献
5.
We describe a new technique to measure the UV/visible absorption spectrum of the ablated material during the laser pulse.
The technique utilizes the continuum emission from one laser produced plasma as a light source to measure the absorption properties
of a second laser produced plasma which is formed on a semi-transparent target with an array of 40 μm holes. A 6 ns, 1064
nm laser was used to ablate a Ag target and the plasma absorption was measured in the range 450–625 nm for a laser fluence
of 1 J cm−2. The total absorption cross-section is (0.5–1.5)×10−17 cm2 in the range 450–540 nm. By comparing the measured absorption with a calculation using the plasma spectroscopy code FLYCHK
it can be concluded that, in the wavelength region examined here, the absorption is mainly due to bound-bound transitions. 相似文献
6.
Excited state absorption and stimulated emission of Nd3+ in crystals. Part 2: YVO4, GdVO4, and Sr5(PO4)3F 总被引:1,自引:0,他引:1
L. Fornasiero S. Kück T. Jensen G. Huber B.H.T. Chai 《Applied physics. B, Lasers and optics》1998,67(5):549-553
3+ ion in the crystals YVO4, GdVO4, and Sr5(PO4)3F. The measurements were performed in the spectral region of the main laser transitions 4F3/2→4I9/2, 4F3/2→4I11/2, and 4F3/2→4I13/2by a continuous wave pump and probe technique. The calibrated gain and ESA spectra are presented and possible implications
of ESA on the laser performance are estimated. It is shown that ESA can be a small loss factor to the laser emission near
1060 nm but does considerably diminish the effective emission cross sections near 1340 nm especially in Nd:YVO4 and Nd:GdVO4.
Received: 29 January 1998/Revised version: 8 May 1998 相似文献
7.
Two-photon optogalvanic transitions in Ar glow discharge with Nd: YAG laser pumped dye laser excitation in the frequency range
13520–16520 cm−1 has been studied using linear and circular polarization. The intensities of two-photon optogalvanic transitions are very
sensitive to changes in the incident laser power which is not the case with one-photon transitions. Intensity ratio for circular
and linear polarized light for two photon transitions 6s′[1/2]°1←4s[3/2]°2, 6s′[1/2]°0←4s[3/2]°2, and 5d[1/2]°0←4s[3/2]°2, 5d[1/2]°1←4s[3/2]°2 are quite different from the other two-photon transitions. This has been explained as due to near one photon resonance
of 4p′[3/2]1 level for the first pair and 4p′[1/2]1 for the second pair of transitions. The ratio of optogalvanic intensity for circular to linear polarized light has
been theoretically estimated and compared with the observed results. 相似文献
8.
Ambartzumian R. V. Furzikov N. P. Letokhov V. S. Puretsky A. A. 《Applied Physics A: Materials Science & Processing》1976,9(4):335-337
A new method of photoionization cross-section measurement based on the observation of saturation in the ion yield as a function
of radiation intensity has been proposed. The photoionization cross-sections for the 62P1/2 and 62P3/2 levels of Rb atoms of the fundamental and second harmonics of ruby laser radiation are measured, with a tunable pulsed dye
laser used for excitation. The following values of cross-sections are obtained: (1.7±0.4)·10−17 cm2 and (1.5±0.4)·10−17 cm2 for the levels 62P3/2 and 62P1/2, respectively, ionized by radiation of v2=14403 cm−1, and (1.9±0.5)·10−17 cm2 for the 62P3/2 level ionized by v2=28806 cm−1 radiation. 相似文献
9.
Some of the low-lying states in many isotopes144Nd,148Sm,152Gd and156Gd show a similar typical behaviour. The first 2+ is regarded as a single quadrupole phonon state and 3− as a single octupole phonon state. The levels with the spins and parities 1−, 5−, 3−, 4−, etc. are considered due to the simultaneous excitation of quadrupole and octupole phonons. If this consideration is correct,
then the transition fromJ
− to 2+ states must contain an appreciableE3 content. Theβ-γ-γ angular correlation coefficients for the cascade ofβ-rays ofE
max 800 keV→γ-rays of 1489 keV→γ-rays of 696 keV are used to estimateE3 content inE1 transition in144Nd. 相似文献
10.
M. L. Hamilton R. Peverall G. A. D. Ritchie L. J. Thornton J. H. van Helden 《Applied physics. B, Lasers and optics》2009,97(3):715-722
We have demonstrated the production of ∼1.9 μm near-infrared radiation by using difference frequency generation within a 5%
MgO doped PPLN crystal by coupling ∼735 nm radiation from a tunable external cavity diode laser with relatively high powered
532 nm radiation from both Nd:YVO3 and Nd:YAG lasers. The radiation produced is of low power, ∼15 μW, and was used in conjunction with the sensitivity enhancing
techniques of wavelength modulation spectroscopy (WMS) and cavity enhanced absorption spectroscopy (CEAS). Experiments were
carried out on rotationally resolved transitions in the combination bands of NH3 and CO2 in the 1.9 μm region. An α
min value of 3.6×10−6 cm−1 Hz−1/2 was achieved for WMS measurements on CO2. A comparable α
min value of 2.2×10−6 cm−1 Hz−1/2 was achieved for NH3 using CEAS. The low NIR power indicates that despite the level of MgO doping quoted for the crystal, under prolonged exposure
photorefractive damage has occurred. 相似文献
11.
State selective stepwise laser photoionization of nitric oxide molecules has been investigated using mass spectroscopic detection
with a quadrupole filter. The ionization was carried out in two steps, the first being excitation with a tunable dye laser
in the (A
2∑+,v′=0.1 state at wavelength around 226 nm and 215 nm, and the second being excitation beyond the ionization limit with a fixed
frequency laser at 266 nm, i.e. the fourth harmonic of a Nd:YAG laser. The sensitivity of NO detection and the mass resolution
of this method has been studied. The ion signal of NO+ was observed with linear pressure dependence at partial densities of NO down to 1×105 cm−3. This corresponds to a density per state of about 2.5×104 cm−3. The mass selectivity was investigated at the various isotopic components of natural nitric oxide14N16O,15N16O,14N18O and the isobare14N17O. 相似文献
12.
R. M. El-Agmy 《Laser Physics》2010,20(11):1990-1993
We report for the first time continuous wave (CW) red laser emission in Tm+3-doped ZBLAN fiber laser, operated at 650 nm (1
G
4 → 3
F
4 transition of Tm+3). The excitation uses a three step upconversion scheme. The pump source is a Nd:YAG laser operated at 1.064 μm. A laser output
power of CW 80 mW was obtained for 1.42 W of launched pump power. The slope efficiency with respect to launched pump power
was measured to be 7.7%. The temporal behavior of the emitted laser is also addressed. 相似文献
13.
Five types of passive Q-switched as well as simultaneously Q-switch mode-locked modulators: plastic dye sheets (Kodak 9850
cellulose acetate dye sheets), lithium fluoride crystals containing F2
− color centers (LiF:F2
−), chromium-doped yttrium–aluminum–garnet crystals (Cr4+:YAG), ionic color filter glass (Schott RG1000 color filter glass), and the single crystal semiconductor wafers (GaAs, Fe-doped
InP, Zn-doped InP, S-doped InP, etc.) used for modulation of the Nd:hosted(Nd:YAG, Nd:YVO4, and Nd:LSB) lasers were investigated in detail in our research. We also investigated applications of the Q-switch mode-locked
pulse train for the development of a higher resolution solid-state laser range finder. 相似文献
14.
M. Takai S. C. Tsou P. H. Tsien D. Röschenthaler H. Ryssel 《Applied Physics A: Materials Science & Processing》1981,24(4):319-322
A Q-switched Nd: YAG laser with a pulse duration of 20 ns was used to investigate effects of laser annealing in gallium implanted
silicon. Rutherford backscattering and Hall-effect measurements were performed to evaluate the annealed layer. Differential
Hall-effect measurements were carried out to obtain carrier concentration profiles after annealing. It was found that a maximum
sheet carrier concentration of 8×1015 cm−2 can be obtained for a gallium implantation of 1016 cm−2 by laser annealing with an energy density of more than 1.0 J cm−2. Although the peak carrier concentration was found to be 8.0×1020 cm−3, the annealed layer showed polycrystalline structures even after annealing with an energy density up to 4J cm−2. The annealing took place in the solid phase in this energy density range. 相似文献
15.
Ye. V. Baklanov V. P. Chebotayev 《Applied Physics A: Materials Science & Processing》1977,13(1):97-99
First cw laser oscillation with thresholds below 1 mW was observed for various B1Пu → X1
∑
g
+
transitions of diatomic molecular sodium excited by different argon laser lines in the range of 454–488 nm. For pump powers
of 0.5 W output powers up to 3 mW and single-pass gain up to 0.1 cm−1 were obtained. Some properties of the heat pipe laser system are discussed. 相似文献
16.
Yu. D. Glinka 《Journal of Experimental and Theoretical Physics》1997,84(5):957-970
It is shown that luminescence detection of multiphoton ionization-fragmentation of the molecular CrO
4
2−
anions adsorbed on the surface of dispersed SiO2 is possible under excitation with the fundamental frequency of a Nd:YAG pulsed laser (λ=1.064 μm). The structure and the process of formation of the adsorbed complexes under thermal activation of the surface and the nature
of luminescence transitions in CrO
4
2−
anions are studied in detail. It is shown that luminescence is excited as a result of the recombination of photoelectrons
and ionized chromate ions. Multiphoton ionization of the ions occurs under three-photon resonance conditions. The resonance
level is an antibonding state of the adsorption complex formed with the participation of an oxygen vacancy on the SiO2 surface. The dynamics of the multiphoton luminescence excitation process includes autoionization (stimulated by intercomplex
electronic excitation) in superexcited states, fragmentation of chromate anions, and annealing of surface oxygen vacancies.
The rate equations for three-photon-resonance multiphoton ionization are studied. The cross sections for two-and one-photon
transitions on the nonresonance steps of multiphoton absorption are obtained. It is concluded that the nonlinear polarizability
of the donor-acceptor adsorption bond in “chromate anion-oxygen vacancy” complexes is very important.
Zh. éksp. Teor. Fiz. 111, 1748–1774 (May 1997) 相似文献
17.
Yu. M. Smirnov 《Journal of Applied Spectroscopy》1998,65(1):5-9
The excitation cross-sections of transitions of a ruthenium atom from the3
S
0−,3
P
0−, and3
D
0-levels are measured by the method of extended crossed beams. Based on the results of measurements, the excitation cross-sections
of the states are calculated (ignoring cascade contribution).
Moscow Power Engineering Institute, 14, Krasnokazarmennaya St., Moscow, E-250, 111250, Russia. Translated from Zhurnal Prikladnoi
Spektroskopii, Vol. 65, No. 1, pp. 9–13, January–February, 1998. 相似文献
18.
A. K. Chaudhary A. M. Rudra P. Kumbhakar G. C. Bhar 《Journal of Applied Spectroscopy》2007,74(4):571-577
We report a technique for the efficient generation of tunable coherent deep UV radiation and its application in studies of
RDX and TNT at the ppm level on the basis of their absorption characteristics. The obtained experimental absorption data are
compared with conventional spectrophotometric data. The UV radiation in the range 200–260 nm has been generated by the type-I
noncollinear third harmonic of the dye laser radiation (600–700 nm) and also by sum frequency mixing (SFM) of Nd:YAG output
(1064 nm) with the second harmonic of the dye laser in β-barium borate (BBO) crystal. The maximum conversion efficiency of
the generated signal is estimated to be 57.5% at λ = 218.9 nm wavelength. Apart from measurements of the absorbance of RDX
and TNT at different concentrations in their respective solutions, the minimum detection concentrations have also been ascertained.
The estimated minimum detectable concentration of RDX is 8.47·10−9 M, whereas that for TNT is 35.7·10−9 M. The data were obtained using only ∼100 μJ/pulse of laser energy.
Published in Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 6, pp. 516–521, July–August, 2007. 相似文献
19.
Triplet-singlet energy transfer in laser dyes have been studied in EPA at 77K using N2 laser as an excitation source. Phosphorescence of the donor (D) and the delayed fluorescence of the acceptor (A) and their
lifetimes have been measured for coumarin 102 (D)-rhodamine B(A) and 9(10H)-acridone (D)-rhodamine 6G(A) dye systems as a
function of acceptor concentration. These data yield energy transfer rate constants of ∼103 dm3 mol−1 s−1 for the donor acceptor combinations, consistent with the Forster mechanism. The phosphorescence quantum efficiency and other
spectral parameters are also reported. 相似文献
20.
Verhoef A. J. Mitrofanov A. V. Nguyen X. T. Krikunova M. Fritzsche S. Kabachnik N. M. Drescher M. Baltuška A. 《Laser Physics》2011,21(7):1270-1274
The cascaded Auger decay following ionization or excitation with 94 eV soft-X-ray pulses from the 3d subshell in krypton has been energy-and-time-resolved for the first time. The decay time of the 4s
−14p
−2
nl → 4p
−3 + e and/or 4s
−14p
−1
nl → 4p
−2 + e transition is measured to be 74 ± 20 fs. Furthermore, our data shows that the electrons with a kinetic energy around 25 eV
(generally assigned as 3d
−1
np → 4s
−2
n′p + e) emitted after core excitation are emitted in a second decay step suggesting an alternative assignment of the form 4s
−2
np 4p
−2 + e. 相似文献