Persistent holes

Patent foramen ovale (PFO) is a small opening that occurs between the two atria in fetuses septums to assist blood circulation. It typically closes shortly after birth and is often incorrectly classified as a form of ASD. The difference between PFOs and secundum ASDs is that PFO occurs as a result of failure of the septum primum and the secundum septum to fuse. Secundum defects on the other hand occur due to the failure of either the septum primum or secundum to overlap correctly. If the foramen ovale does not close, the result is a persistent hole which places an increased workload on the lungs and on the right side of the heart. ... 

It is interesting to note that persistent holes can be burned into the inhomoge-... 

Fujita K., Hirao K Soga N. Room-temperature persistent hole burning of Eu + in sodium aluminosilicate glasses. Opt. Lett. 1998 23 543-545... 

Masumoto Y., Kawabata K., Kawazoe T. Quantum size effect and persistent hole burning of Cul nanocrystals. Phys. Rev. B 1995 52 7834-7837... 

Moerner W.E., Sievers A.J., Silsbee R.H., Chrapl3rvy A.R., Lambert D.K. Persistent holes in the spectra of localized vibrational modes in crystalline solids. Phys. Rev. Lett. 1982 49 398-401... 

Fig. 1. PS II reaction center low temperature spectra. Top 4.2 K absorption spectrum of preparation A (dashed line) and B (solid line). Optical density at P680 maximum is 0.2 and 0.5, respectively. Bottom persistent hole burned spectrum of preparation A (dashed line) and preparation B (solid), 4.2 K. Bum wavelength (A. ) for each spectrum is coincident with the sharp zero-phonon hole near 665 nm. The broad ( 120 cm" ) Pheo a satellite holes at 681.6 nm (preparation A) and 681.3 nm (preparation B) are due to energy transfer from the Chi a pigments excited at Xg. The Pheo a holes represent a peak percent absorbance change of 7%. Hole burning conditions Ig = 200 mW/cm Tg = 20 min Tg = 4.2 K...

Fig. 2. Persistent hole burned spectra of PS II RC with Ag = 632 nm (trace 1) and A.g = 662 nm (trace 2). The satellite hole at 546 nm is due to the Q -state of Pheo a. Trace 3 is the non-line narrowed transient hole spectrum of P680 (A,g = 662 nm). Trace 4 is due to bleaching of Pheo a obtained with white light illumination in the presence of dithionite. All experiments performed at 4.2 K...

Fig. 7. Absorption and persistent hole burned spectra of PS II RC in the presence of 0.03% Triton X-100, 4.2 K. Hole burning conditions see Fig. 1 A.g = 664.8 mn. Note marked diminuation in intensity of broad satellite hole at 681.6 nm, cf. Fig.l. Features (hole) at 260, 347 and 385 cm are Chi a vibronic satellite holes associated with the ZPH at Xg, see text...

The HB method became the main one for selective sj troscopy due to the existence of long life persistent holes. It turned out that percent hol living at low temperature even for days can be burnt in many important organic and inorganic systems. The persistent holes appear because chromophoies, after their excitation by light, relax to a metastable ground electronic state which is separated from the initial ground state by a potential barrier. Persistent holes can be erased if we heat our sample. 

The extrinsic TLS are created in polymers by an embedded chromophore. The extrinsic TLS is closely related to the adiabatic potential of a chromo-phore.These TLS are characteristic of a couple chromo[ ore polymer. It is obvious that the number of the extrinsic TLS is proportional to the chromophore concentration. These very TLS are responsible for the burning of persistent holes in a chromophore optical band (Fig. 22). 

Figure 3 Three levels are necessary for persistent hole burning. Po has a long lifetime and acts as a storage state.

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