Absorption neodymium

The light source for excitation of Nd YAG lasers may be a pulsed flashlamp for pulsed operation, a continuous-arc lamp for continuous operation, or a semiconductor laser diode, for either pulsed or continuous operation. The use of semiconductor laser diodes as the pump source for sohd-state lasers became common in the early 1990s. A variety of commercial diode-pumped lasers are available. One possible configuration is shown in Figure 8. The output of the diode is adjusted by composition and temperature to be near 810 nm, ie, near the peak of the neodymium absorption. The diode lasers are themselves relatively efficient and the output is absorbed better by the Nd YAG than the light from flashlamps or arc lamps. Thus diode-pumped sohd-state lasers have much higher efficiency than conventionally pumped devices. Correspondingly, there is less heat to remove. Thus diode-pumped sohd-state lasers represent a laser class that is much more compact and efficient than eadier devices. 

Part of the absorption spectrum of an aqueous solution of neodymium(iii) -configuration/ - is shown in Fig. 10-4. The situation shown there is quite typical of the whole of the lanthanoid series i.e. we could have chosen any/" configuration equally well to illustrate the main characteristics of the spectra of lanthanoid complexes. We shall focus on three main features splittings, band widths and absolute excitation frequencies. 

Figure 1. The near IR absorption spectrum of anhydrous liquid hydrofluoric acid with a few of the many possible IR wavelengths obtainable from a neodymium-doped glass laser superimposed.

Figure 8.7. Delayed fluorescence and diffuse reflectance transient absorption spectroscopy on scattering substrates. Example terthicnyl on silica gel excited with = 354 nm (neodymium/yttrium-aluminum-garnet) (Nd/YAG) laser pulse of 10 nsec, 20 mj), recorded with a gated diode array spectrometer.

S - S absorption and intersystem crossings from the state of naphthalene in cyclohexane at room temperature were studied by Bonneau et al i using a neodymium laser ( X = 1.0 /x,... 

Neodymium may be analyzed by x-ray diffraction, x-ray fluorescence, atomic absorption, or atomic emission spectrometry. Also, the metal may be identified and measured by neutron activation analysis. 

The third oxide used for physical decolorizing is neodymium oxide. Its absorption curve closely compliments an average mixture of ferrous and ferric oxides especially with the strong absorption band at 589 nm. Neodymium oxide is also stable against any state of oxidation change in the furnace. Neodymium is exceptionally good as a decolorizer for potassium silicate and lead glasses. If the redox balance is not quite correct for the... 

The most important application of the nonlinear absorption characteristics of dye solutions is the so-called passive Q-switching of solid-state lasers, in particular ruby lasers emitting at 694.3 nm and neodymium lasers emitting at 1.064 /tm. 

Q-switch dyes for neodymium lasers are not so numerous since there are only relatively few dyes known which exhibit absorption due to an electronic transition... 

Recently, a new Q-switch for neodymium lasers has become available 29> which is extremely stable and shows energy-dependent Q-switching similar to the phthalocyanines by a rapid intersystem crossing into the triplet state 30>. This "dye is a nickel-complex, bis-[p-dimethylamino]-dithiobenzylnickel, and has a strong absorption band around 1 / in several solvents. 

This scheme of frequency tripling was successfully tested with fuchsin in hexafluorisopropanol (a solvent selected for its low index of refraction and relatively flat dispersion curve) to frequency-triple the output of a neodymium laser 67,68) With an input power of 10 MW/cm2 a third-harmonic output of 0.2 mW/cm2 was measured. This low value was mainly due to the relatively high absorption of fuchsin at 355 nm. An improvement of the efficiency by a factor of 80 was found with hexamethylindocarbocyanine iodide in hexafluorisopropanol because of the much lower absorption of this dye at 355 nm. Since the absorption minimum of this dye is at 383 nm, one could expect an additional efficiency increase by a factor of 70 for a fundamental laser wavelength of 1.15 / 69>. Other cyanine dyes have been used for frequency tripling a fundamental wavelength of 1.89 /mi 70>. 

The aF3,2- 4F5,2 emission of Nd3+ at 885 nm can also be monitored in a rather similar way, and a study of emission lifetimes together with absorption spectra for the hypersensitive Nd3+ transitions, e.g. %/2- 4Gs/2, has been made in order to investigate the solvation of neodymium nitrate and perchlorate in MeCN, Me2CO, DMSO or DMF. Excited lifetimes varied from 300 ns in Me2CO to 2300 ns in CD3CN. It was found that species Nd(N03) (3 ")+ were formed, where n = 1-5, on addition of NOJ ions to perchlorate solutions, but that addition of DMSO to Nd(CI04)3 in MeCN gave [Nd(DMSO) ]3+, where n = 9.7 0.8.618... 

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