Optical centrifuge

Figure 10.8 Examples of controlling rotational wave packets with an optical centrifuge. Shifting the center of a narrow wave packet is shown for centrifuged oxygen on (a), whereas varying the width of the wave packet is demonstrated for nitrogen on (b). Black dots represent the thermal distribution at room temperature.

In the recent work reviewed in this chapter, we have shown the creation and properties of molecular superrotors, illustrated by application of the optical centrifuge to simple diatomic molecules. The technique is certainly not limited to diatomics, and to date we have created superrotor wave packets in a range of molecules. All that is required is an anisotropic polarizability such that the molecule can be... 

A. Korobenko, A. A. Milner, J. W. Hepburn, and V. Milner. Rotational spectroscopy with an optical centrifuge. Phys. Chem. Chem. Phys., 16(9) 4071 076 (2014). 

The optical centrifuge is capable of imparting so much rotational energy to a diatomic molecule that the bond breaks. To see how this happens, note that the effective radial potential seen by a diatomic molecule is a sum.of its real potential V(R) and a centrifugal one associated with its angular motion. That is, the vibrational motion sees the effective potential... 

Sizing of Pyrogenic Aggregates with Optical Centrifugation and DLS... 

A typical result of this comprehensive characterisation is exemplarily shown for one material in Fig. 4.30. In this example, as for all other powders, the measured size distributions complied with the expectations from theory. That is, the backscattering DLS instrument measures slightiy finer distributions than the 90°-DLS instrument and both yield considerably coarser distribution functions than the optical centrifuge. Additionally, there is a systematic difference between the distribution widths of the DLS instruments, which can be assigned to the specific inversion algorithms. Indeed, polydispersity values obtained by the method of cumulants (Eq. 2.34) perfectly agreed. ... 

Fig. 4.30 Measured size distributions from optical centrifugation analysis (OCA) and dynamic light scattering (90° and 173°), i.e. distribution of the effective hydrodynamic diameter Xi, efl 9o /i73° weighted by seattering intensity as well as of the Stokes diameter JtstokEs weighted by optical extinction pyrogenic silica (BET = 50 m /g)...

---