Hemoglobin (Hb) is the heme-containing O2 transport protein essential for life in all vertebrates. The resting high-spin (S = 2) ferrous form, deoxy-Hb, combines with triplet O2, forming diamagnetic (S = 0) oxy-Hb. Understanding this electronic structure is the key first step in understanding transition metal-O2 interaction. However, despite intense spectroscopic and theoretical studies, the el...

Competing electronic pathways exhibiting energy dependence across a single vibronic excitation are observed in β-carotene for the first time with broadband two-dimensional electronic spectroscopy at 77K. The origins and implications of these features are discussed.

As for carbon nanotubes, optical and vibrational spectroscopy in particular Raman and luminescence spectroscopy play an important role for the characterization of BN nanotubes. In this chapter we review, from a theoretical view point, the different spectroscopic techniques that are currently used for BN-nanotubes and make a close link with available experimental data. We summarize experimental ...

Intermolecular electronic coupling dictates the optical properties of molecular aggregate systems. Of particular interest are photosynthetic pigment-protein complexes that absorb sunlight then efficiently direct energy toward the photosynthetic reaction center. Two-dimensional (2D) ultrafast spectroscopy has been used widely in the infrared (IR) and increasingly in the visible to probe excitoni...

Minhaeng Cho,* Tobias Brixner, Igor Stiopkin, Harsha Vaswani and Graham R. Fleming* Department of Chemistry and Center for Multidimensional Spectroscopy, Division of Chemistry and Molecular Engineering, Korea University, Seoul 136-701, Korea Department of Chemistry, University of California, Berkeley, Berkeley, California 94720 and Physical Biosciences Division, Lawrence Berkeley National Labor...

The properties of molecular aggregates, coupled clusters of small molecules, are often challenging to unravel because of their inherent complexity and disordered environments. Their structure-function relationships are often far from obvious. However, their ability to efficiently channel excitation energy over remarkable distances, as is the case in photosynthetic light harvesting, is a compell...

Two-dimensional (2D) spectroscopy is a powerful technique to study nuclear and electronic correlations between different transitions or initial and final states. Here we describe in detail our development of inherently phase-stabilized 2D Fourier-transform spectroscopy for electronic transitions. A diffractive-optic setup is used to realize heterodyne-detected femtosecond four-wave mixing in a ...

In this paper, we present the first gas-absorption spectra measured with an all-electronic terahertz spectrometer. This instrument uses phase-locked microwave sources to drive GaAs nonlinear transmission lines that produce picosecond pulses, enabling measurement of broad-band spectra. By sweeping the fundamental excitation, however, the spectrometer can also measure single lines with hertz-leve...