Laser spin atomization

The Laser-spin-atomized droplets are usually spherical, clean, and homogeneous in composition. A mass median diameter of 100 pm has been obtained for a Ni-Al-Mo alloy. Cooling rates are estimated to be in the order of magnitude of 105 °C/s. Similarly to other centrifugal atomization techniques, droplet properties (shape, size, cooling rate, etc.) are dependent on the rotation speed, ingot diameter, superheat, and material properties. 

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Laser Spin Atomization -100 Ni-Al-Mo, Ti-6A1-4V 105 — — Spherical, homogeneo us, clem particles Low volume productivity, Poor EE, Cost... 

A complex dynamical behavior was experimentally and numerically found in a system of spin- atoms in an optical resonator with near-resonant cw laser light and external static magnetic field [69]. Three-dimensional Bloch equations were solved, and a chaotic motions was found and compared with experiment. 

At temperatures of 1 K, all substances except for He (and certain spin-polarized species, such as atomic hydrogen) have negligible vapor pressure, so the question arises as to how to bring the species to be cooled into the gas phase and then into the buffer gas. Five methods have been used to accomplish this laser ablation, beam injection, capillary filling, discharge etching, and laser-induced atom desorption (LIAD). 

Section 4 contains an analysis of the proper description of the state of the system which is initially prepared in a collision experiment involving a laser-excited atom. Here an adiabatic analysis will be used to point out several inadequacies in simple semiclassical treatment of these spin-changing transitions. Finally, section 5 is devoted to a presentation of the orbital-locking models of Hertel and co-woikers [10-12]. The insights gained in our more exact quantum treatment will be used to examine critically the validity of these models. A brief conclusion follows. 

Several characteristics of the metal beam have been studied in detail. It is well known that metal clusters and metal oxides are formed as a result of the ablation process. However, these potentially interfering species have been studied in detail130 and it has been concluded that they do not introduce any doubt as to the validity of the experimental results. Much more important than cluster or oxide formation are the atomic electronic state populations of the metal beams. For each metal reactant, these have been characterized using laser-induced fluorescence (LIF) excitation spectroscopy. For Y, only the two spin-orbit states of the ground electronic state (a Dz/2 and a D-3,/2) were observed.123... 

Within its orbit, which has some of the characteristics of a molecular orbital because it is shared with electrons on the surrounding atoms, the electron has two possible spin multiplicity states. These have different energies, and because of the spin-multiplicity rule, when an (N-V) center emits a photon, the transition is allowed from one of these and forbidden from the other. Moreover, the electron can be flipped from one state to another by using low-energy radio-frequency irradiation. Irradiation with an appropriate laser wavelength will excite the electron and as it returns to the ground state will emit fluorescent radiation. The intensity of the emitted photon beam will depend upon the spin state, which can be changed at will by radio-frequency input. These color centers are under active exploration for use as components for the realization of quantum computers. 

Sometimes the atoms (or molecules) in molecular beams are put into selected electronic, vibrational and rotational states. The initial state selection can be made with lasers. A laser beam of appropriate frequency is shined onto a molecular beam and the molecule goes onto an appropriate excited state. The efficiency of selection depends upon the absorption coefficient. We can attain sufficient absorption to get highly vibrationally excited molecule with the laser. A spin forbidden transition can also be achieved by using a laser. 

The fine structure intervals of the alkali atoms often fall in the 1-10 MHz range, in which case the transition between spin orbit and uncoupled states can be made either diabatically or adiabatically. Jeys et al.16 have observed the transition from an adiabatic to a diabatic passage from the coupled fine structure states to the uncoupled states. With a pulsed laser, they excited Na atoms from the 3p1/2 state to the 34d3/2 state with o polarized light, which leads to 25% my = 1/2 atoms and... 

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