Cooling transition

Figure Cl.4.9. Usual cooling (carrier) and repumping (sideband) transitions when optically cooling Na atoms. The repumper frequency is nonnally derived from the cooling transition frequency with electro-optic modulation.

The temperature then drops to a value limited by the 3 °K black body background radiation and is controlled by the temperature of the grains and the ionization by high energy cosmic rays on the one hand, and saturation of the cooling transitions on the other. 

Two kinds of ion species are involved depending on their atomic level properties. One has two optical/peripheral electrons, such as A1+, In+, where the clock transition is based on a dipolar electric transition, and the other has only one optical electron, such as Ca+, Hg +, Sr+, and Yb+, for which the clock transition is based on either a quadrupolar or an octopolar dipole electric transition. With the first kind of ion, the cooling transition is cycling wherein 100% of the atoms relax to the lower level, while the cooling transition (nS to nP) of the second kind relaxes to two different-orbital lower levels the fundamental ( 5) and one metastable level ((n-1) D). The value of the relaxation branching ratio between the nS and metastable (n-1) D levels is such that a significant fraction of ions will populate the metastable (n-l)D level. Thus, another laser is required to pump the atomic ions from the (n-l)D level back to the optically excited state nP. 

TABLE 1. Comparison of Phospholipid Liquid Crystalline - Crystalline (Cooling) Transition with Nerve Membrane During Excitation... 

Table I shows the thermotropic transitions of phospholipids and vesicle dispersions of 1 and 2, along with enthalpies of transition. NCP-1 shows a sharp chain melting transition temperature at 37.5 C and a sharper transition peak at 32.8 C upon cooling. The AH at 37.5 C was determined to be 6.07 kcal/mole. Dispersions of the NCVD-1 show a chain melting transition at 25.9 C and a cooling transition at 23.6 C. CVD-1 shows a melting transition at 29.4 °C and a cooling transition at 25.9 C.

Measurements were recorded on the thermotropic chain melting and cooling transitions of CVD-1 with the hydrophobic dye oil red-0 entrapped within the lipophilic membrane. A chain melting transition was found at 15.3 C and a cooling transition was seen at 13.1 C. There is a 14 C difference in the transition of the cross-linked vesicles without dye entrapped and the cross-linked vesicles with dye entrapped. The AH value was shown to be 0.055 kcal/mole at 15.3 C. 

The significance of this observation and deduction became important in the study of 2 1 complexes of stilbazoles with 1,3-diiodotetrafluorobenzene (Figure 51). Remarkably, these complexes showed (monotropically) a cooling transition sequence of Iso-N-N, despite the fact that there was no chiral component. In analyzing the behavior, it was found to be consistent with interpretation where the nematic phase originated predominantly from... 

The average of the heating and cooling transition temperature 7 is given. Not determined. 

Hydrogen bond relaxes under the coupling of multiple fields and responses independently. Cooling in liquid and solid phase effect the same to water under compression to shortens the 0 H nonbond and lengthen s the H-O bond. Molecular undercoordination effects the same to the cooling transition from water to ice, which shortens the H-O bond and lengthens the 0 H nonbond. 

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