FM-Stark

Fig. 2.3. (A) Illustration of the crystal structure of p-terphenyl, with a single substitutional impurity of pentacene. (B) Single molecules of pentacene in p-terphenyl detected by FM-Stark optical absorption spectroscopy, (a-c) Simulated traces for absorption, FM and FM-Stark, respectively. The W -shaped structure in the center of trace (d) is the absorption from a single pentacene molecule, acquired multiple times to show repeatability, (e) Average of traces in (d) with expected hneshape. Trace (f) is the signal from a region of the spectrum with no molecules, while trace (g) is a region with many molecules showing SFS. For details, see [3,26]...

The first SMS experiments in 1989 utilized either of two powerful doublemodulation FM absorption techniques, laser frequency-modulation with Stark secondary modulation (FM-Stark) or frequency-modulation with ultrasonic strain secondary modulation (FM-US) [3,26]. The secondary modulation was required in order to remove the effects of residual amplitude modulation produced by the imperfect phase modulator. In contrast to fluorescence methods, Rayleigh and Raman scattering were unimportant. Figure 2.3B (specifically trace d) shows examples of the optical absorption spectrum from a single molecule of pentacene in p-terphenyl using the FM-Stark method. 

Figure 6. The first single-molecule optical spectra, showing use of the FM/Stark technique for pentacene in />-terphenyl. (a) Simulation of absorption line with (power-broadened) linewidth of 65 MHz. (b) Simulation of FM spectrum for (a), com = 75 MHz. (c) Simulation of FM/Stark line-shape, (d) single-molecule spectra at 592.423 nm, 512 averages, 8 traces overlaid, bar shows value of 2o)m = 150 MHz. (e) Average of traces in (d) with fit to the in-focus molecule (smooth curve), (f) Signal far off line at 597.514 nm. (g) Traces of SFSatthe O2 line center, 592.186 nm. After Ref. 1.

Hieraus ist ersichtlich, daB die spontanen Kemspaltungshalbwerts-zeiten der geradzahligen Isotope der Elemente mit gerader Ordnungszahl iiber ein Maximum verlaufen (s. Th, U, Pu, Cm). Bei Erreichen der Neutronenzahl N = 152 nehmen sie jedoch plotzlich stark ab (Cm, Cf, Fm). (Die Kurven fur die Elemente 102, 104 und 106 sind extrapoliert.)... 

Bubenhofer SB, Schumacher CM, Koehler FM, Luechinger NA, Grass RN, Stark WJ Large-scale synthesis of PbS—Ti02 heterojunction nanoparticles in a single step for solar cell application, J Phys Chem C 116 16264—16270, 2012. 

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