Vaporization cell

Gas/Vapor Cell Width (cm) Gas/Vapor Cell Width (cm)... 

Heating of Electrically Heated Nonflame Atomic Vapor Cells". Anal. Chem. (1975), 38-45. 

Jongerius MJ, Van Bergen ARD, Hollander T, Alkemade CTH (1981) An experimental study of the collisional broadening of the Na-D lines by Ar, N2 and H2 perturbers in flames and vapor cells—I. The line core. J Quant Spectrosc Radiat Transfer 25 1-18... 

The ball-value is a special type of vaporization cell (Fig. 8 i) which is used for the high pressure range from 10 to 760 torr. Depending on the temperature range, the material of the cell and of the ball may be Al, steel, gold or sapphire. The ball is situated on top of the cell so as to form a valve which opens when the inside pressure is higher than the outside pressure plus the weight of the ball. 

In spite of the fact that in alkali vapors, which contain about 1 % diatomic alkali-molecules at a total vapor-pressure of 10 torr, the atoms cannot absorb laser lines (because there is no proper resonance transition), atomic fluorescence lines have been observed 04) upon irradiating the vapor cell with laser light. The atomic excited states can be produced either by collision-induced dissociation of excited molecules or by photodissociation from excited molecular states by a second photon. The latter process is not improbable, because of the large light intensities in the exciting laser beam. These questions will hopefully be solved by the investigations currently being performed in our laboratory. 

The counting rate (dN/dt) should be made as high as possible. From this point of view the experiments on vapor cells, like that planned for PbO, have a clear advantage as compared to beam experiments... 

It is crucial to attain high coherence time T. In the beam experiments that time is just the time of flight through the region with the electric held. For a gas-dynamic molecular source the typical time of flight is 1 — 10 ms. On the other hand, for the PbO experiment in vapor cell T is close to the lifetime of the excited (metastable) state a(l), T 0.1 Ills. So, the beam experiments have advantage in the coherence time. 

Figure 1. Sketch of vaporization cell showing boundary conditions and hypothetical concentration profiles...

Cotton G. Wilkinson, Advanced Inorganic Chemistry. . Interscience, NY (1966), 418 4) M.P.R. Thomsen et al, Improved Rubidium Vapor Cells for Frequency Standards , Rept No 7366-F, Melpar Inc, Fall Church, Contract DAAB07-67-C-O535 (1968) 5) Ibid, Rept No... 

Figure 2. A - Experimentally measured and theoretically calculated values of dns/dt, the number of Stokes photons per unit time emitted from the atomic vapor cell. For each plot, ns = f dt dns/dt represents the total number of photons emitted from the cell. The write laser power is varied from 25 mW to 100 mW. B - Experimentally measured and theoretically calculated values of dnAs/dt, the number of anti-Stokes photons per unit time emitted from the atomic vapor cell. The experimental pulse shapes correspond to a Stokes pulse with ns 3 photons, and the theoretical curves assume an initial spin wave with nspin = 3 excitations and an optical depth of 20. Each curve is labeled with the power of the retrieve laser. Inset theoretical calculation of the number of flipped spins per unit length dnspin/dt as a function of position in the atomic cell, for nspin = 3. C - Measured anti-Stokes pulse width (full-width at half-maximum) and total photon number as a function of the retrieve laser intensity. Lines are intended only to guide the eye.

We have applied the method outlined above to the selective generation and study of polarization moments of 87Rb atoms contained in a vapor cell with antirelaxation coating. Our experimental setup is shown in Fig. 8 [Yashchuk 2002], The cell is placed between a polarizer and an analyzer oriented at 45° with respect to each other and contains an isotopically enriched sample of 87Rb atoms with a density 7.109 cm-3 at 20°C. The central laser frequency is tuned near various hyperfine structure components of the D line. The typical light power is a few hundred // W and the laser beam diameter is 3 mm. The laser frequency is modulated at Q,/(27r) from 50 Hz to 1 kHz, and the frequency modulation amplitude is 40 MHz (peak to peak). The vapor cell is... 

An ensemble of cold Rydberg atoms is easily obtained after laser excitation of a cold atomic cloud, as those performed in a Gs or lib vapor-cell magnetooptical trap, at a temperature of 135 /jK or 300 fiK respectively. In the case of cesium (for the experiments performed at Laboratoire Aime Cotton) or rubidium (for the experiment performed at the University of Virginia), the atoms p-excited by the cooling lasers are Rydberg-excited by using a laser pulse provided by a dye laser pumped by the third harmonic of a Nd YAG laser... 

Step 3 You can then use Goal Seek to make the Rachford-Rice equation (cell F9) zero by changing the fraction of the feed that is vapor (cell DI), giving the result shown. Once you find the fraction vapor, the mole fractions in the two phases are easy to calculate using Eqs. (3.8) and (3.1), and these are included in columns G and H. 

Monroe C, Swann W, Robinson H and Wieman C 1990 Very cold trapped atoms in a vapor cell Phys.Rev.Lett. 65 1571-4... 

Figure 25-20. Potential differences measured on air/hydrogen, water vapor cells with platinum electrodes prepared with different layer thickness resistivity ratios d/p (a), or after annealing at different temperatures between 500 and 1300 °C (b) [73].

Laser Fluorescence Noise Sources. Finally, let us examine a technique with very complex noise characteristics, laser excited flame atomic fluorescence spectrometry (LEAFS). In this technique, not only are we dealing with a radiation source as well as an atomic vapor cell, as In atomic absorption, but the source Is pulsed with pulse widths of nanoseconds to microseconds, so that we must deal with very large Incident source photon fluxes which may result in optical saturation, and very small average signals from the atomic vapor cell at the detection limit [22]. Detection schemes involve gated amplifiers, which are synchronized to the laser pulse incident on the flame and which average the analyte fluorescence pulses [23]. 

Fig. 4.16 Section of the excitation spectrum of NO2 obtained under different experimental conditions (a) in a vapor cell at T = 300 K, p(N02) = 0.05 mbar (b) in a pure NO2 beam at rot = 30 K (c) in a supersonic argon beam seeded with 5 % NO2 at rot — 3 K, where (a-c) were excited with a dye laser with 0.05 nm bandwidth [413] (d) 0.01 nm section of (b) recorded with a single-mode dye laser (1 MHz bandwidth) [414]...

Level-crossing spectroscopy with lasers has some definite experimental advantages. Compared with other Doppler-free techniques it demands a relatively simple experimental arrangement. Neither single-mode lasers and frequency-stabilization techniques nor collimated molecular beams are required. The experiments can be performed in simple vapor cells, and the experimental expenditure is modest. In many cases no monochromator is needed since sufficient selectivity in the excitation process can be achieved to avoid simultaneous excitation of different molecular levels with a resulting overlap of several level-crossing signals. 

Optical pumping with lasers may bring an appreciable fraction of all atoms within the volume of a laser beam passing through a vapor cell into an excited electronic state. This allows the observation of collisions between two excited atoms, which lead to many possible excitation channels where the sum of the excitation energies is accumulated in one of the collision partners. Such energy-pooling processes have been demonstrated for Na + Na, where reactions... 

The KRb experiments take place in a dual-species vapor-cell MOT [45]. Diode lasers at 767 and 780 nm are used to cool and trap K and Rb atoms, respectively, in the dark-spot MOT configuration. Atomic densities of 3 x lO cm" for K and 1 x 10 cm for Rb are realized, with corresponding temperatures of 300 and 100 tiK. Photoassociation is induced by illuminating the overlapping cold atomic clouds with light from a tunable cw titanium-sapphire laser (Coherent 899-29). This laser typically provides 500 mW with a linewidth of 1 MHz and its output is focused down to approximately match the size ( 300 p,m diameter) of the cold atom clouds. 

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