Saturation pumping

Thus we see that, although collisional effects do reduce the degree of controlji relative to the collision-free case, saturation pumping of superposition in the bichro- ) matic control scenario can be used to overcome collisional effects up to somejli reasonable temperature. 

The probe beam is split by the plane-parallel plate Pll into two beams. One beam passes through that region of the absorbing sample that is saturated by the pump beam the other passes through an unsaturated region of the same sample cell. The two beams are recombined by a second plane-parallel plate P12. The two carefully aligned parallel plates form a Jamin interferometer [273], which can be adjusted by a piezoelement in such a way that without the saturating pump beam the two probe waves with intensities I and h interfere destructively. 

Magnetic flow meters are the preferred choice for brine feed flow measurement. If the saturator pump tank level is controlled by throttling the brine to the treatment tanks, as in Fig. 11.3a, the measurement shown in Fig. 11.4 gives the net brine flow through the system. It is used to detmnine the quantities of the treatment chemicals to be added. If the tank level control is through the recycle of the clarified brine, as in Fig. 11.3b, measurement of the recycle flow as well as the feed flow allows calculation of the net feed by subtraction. The resultant value can then be used to control the rates of addition of the treatment chemicals. The brine flow signal in Fig. 11.4 does not reflect the latter approach. 

II. 2 - There is a directional anisotropy of the saturation in the case when only one of the pumps is saturating, the PC lineshape differs if the saturating pump is either the forward or the backward pump [4]. This anisotropy is a direct consequence of the atomic velocity distribution. Its physical... 

The saturating pump laser with the wave vector which is kept at the... 

Contrary to the situation in polarization spectroscopy, where for slightly uncrossed polarizers the line shape of the polarization signal is a superposition of Lorentzian and dispersion profiles, with saturated interference spectroscopy pure Lorentzian profiles are obtained. Measuring the first derivative of the profiles, pure dispersion-type signals are obtained. To achieve this, the output of the lock-in amplifier that controls the phase is fed into another lock-in, tuned to a frequency f2 (f2 fi) at which the saturating pump beam is chopped. 

The population density n (v) is altered by the saturating pump transition a b. With a pump laser frequency we obtain, according to (10.20),... 

Inserting (10.32) into (10.31) yields the absorption coefficient a(w2) of the probe wave in the presence of the saturating pump wave at frequency... 

The second lock-in filters the desired signal caused by the saturating pump beam out of all other background which may cause a phase shift. 

If cold saturated ethanolic solutions of the recrystallised tetrahydrocarbazole and of picric acid are mixed and stirred, the chocolate-brown picrate of the carbazole slowly crystallises. After it has been filtered off at the pump, washed with a small quantity of ethanol, and dried, it has m.p. 145-146°. 

Add 0-5-1 ml. of the alcohol, cork the flask loosely, and heat on a water bath for 10 minutes secondary and tertiary alcohols require longer heating (up to 30 minutes). Cool the mixture, add 10 ml. of 5 per cent, (or saturated) sodium bicarbonate solution, break up the resulting solid ester with a stirring rod (alternatively, stir until crystalline), and filter at the pump wash with a little sodium bicarbonate solution, followed by water, and then suck as dry as possible. Dissolve the crude... 

Prepare 10 ml. of saturated sodium bisulphite solution and add 4 ml. of the aldehyde shake thoroughly and observe the rise in temperature. Filter the crystalline precipitate at the pump, wash it with a little alcohol, followed by ether, and allow it to dry. 

Prepare a saturated solution of sodium bisulphite at the laboratory temperature from 40 g. of finely powdered sodium bisulphite about 70 ml. of water are required. Measure the volume of the resulting solution and treat it with 70 per cent, of its volume of rectified spirit (or methylated spirit) add sufficient water (about 45 ml.) to just dissolve the precipitate which separates. Introduce 20 g. of commercial cycZohexanone into the aqueous-alcoholic bisulphite solution with stirring and allow the mixture to stand for 30 minutes stir or shake occasionally. FUter off the crystalline bisulphite compound at the pump, and wash it with a little methylated spirit. 

Pour the resulting dark reddish-brown liquid into 500 ml. of water to which 17 ml. of saturated sodium bisulphite solution has been added (the latter to remove the excess of bromine). Steam distil the resulting mixture (Fig. II, 41,1) , collect the first portion of the distillate, which contains a little unchanged nitrobenzene, separately. Collect about 4 litres of distillate. Filter the yellow crystalline solid at the pump, and press well to remove the adhering liquid. The resulting crude m-bromonitrobenzene, m.p. 51-52°, weighs 110 g. If required pure, distil under reduced pressure (Fig. II, 19, 1) and collect the fraction of b.p. 117-118°/9 mm. it then melts at 56° and the recovery is about 85 per cent. 

Dissolve 3-5 g. of aniline hydrochloride in 20 ml. of absolute ethyl alcohol contained in a 50 ml. conical flask, and add 0-5 ml. of a saturate solution of hydrogen chloride in absolute ethyl alcohol. Cool in ice and add 4 g. (4 -6 ml.) of iso-amyl nitrite (compare Section 111,53) gradually. Allow the mixture to stand for 5-10 minutes at the room temperature, and precipitate the diazonium salt by the gradual addition of ether. Filter ofiF the crystals at the pump on a small Buchner funnel, wash it with 5 ml. of alcohol - ether (1 1), and then with 10 ml. of ether. Keep... 

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