Excited-state dynamics of carotenoids in light-harvesting complexes. 2. Dissecting pulse structures from optimal control experiments.
Dispersed multipump-probe (PPP) spectroscopy was used to explore the role of saturation, annihilation, and structured pulses in recent coherent control experiments on the light-harvesting 2 complex from Rhodopseudomonas acidophila (Herek et al. Nature 2002, 417, 533). We discuss the complimentary aspects between the PPP technique and coherent control studies, in particular the ability to dissect complicated pulse structures and the utility in exploring incoherent mechanisms. With the aid of a simple multistate model involving only population dynamics, we illustrate how the optimized structured pulses may be explained in terms of an interplay between excited-state populations, saturation, and annihilation. Furthermore, we discuss the experimental conditions that are required for incoherent effects to contribute to control experimental signals, with particular emphasis on pulse intensities, and show that the optimization of a ratio of conservative signals (i.e., not modulated by external dynamics) is required to exclude saturation effects from coherent control studies.
Faculty of Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands.
Emmanouil
E
Papagiannakis
Mikas
M
Vengris
Leonas
L
Valkunas
Richard J
RJ
Cogdell
Rienk
R
van Grondelle
Delmar S
DS
Larsen
D002338:Carotenoids / Q000737:chemistry* / Q000378:metabolism; D004735:Energy Transfer; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry* / Q000378:metabolism; D008954:Models, Biological; D012241:Rhodopseudomonas / Q000737:chemistry*; D013057:Spectrum Analysis; D013997:Time Factors
D045342:Light-Harvesting Protein Complexes; D002338:Carotenoids