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Donor-Acceptor (D-A) systems based on phenoxazine – phthalocyanine (PXZ-Pc) and phenoxazine – zinc phthalocyanine (PXZ-ZnPc) have been designed and synthesized. Both D-A systems are characterized using various spectroscopic and electrochemical techniques including in-situ methods. Optical absorption studies suggest that both Soret and Q bands of these D-A systems are hypsochromically and bathochromically shifted, when compared to its individual constituents. The study supported by theoretical calculations shows clearly that there exists a negligible electronic communication in the ground state between donor phenoxazine and acceptor phthalocyanine. However, attractively, both D-A systems exhibit noteworthy fluorescence emission quenching (90–99%) of the phthalocyanine emission compared to its reference compounds. The fluorescence emission quenching featured at the excited-state intramolecular photoinduced electron transfer from ground state of phenoxazine to the excited state of phthalocyaine/zinc phthalocyanine. The rates of electron-transfer ($k_{ET})$ of these D-A systems are found in the range of 5.7 × 10⁸ to 2.8 × 10⁹ s${}^{-1}$ and are according to solvent polarity.

Time-resolved flow cytometry (TRFC) was used to measure metabolic differences in estrogen receptor-positive breast cancer cells. This specialty cytometry technique measures fluorescence lifetimes as a single-cell parameter thereby providing a unique approach for high-throughput cell counting and screening. Differences in fluorescence lifetime were detected and this was associated with sensitivity to the commonly prescribed therapeutic tamoxifen. Differences in fluorescence lifetime are attributed to the binding states of the autofluorescent metabolite NAD(P)H. The function of NAD(P)H is well described and in general involves cycling from a reduced to oxidized state to facilitate electron transport for the conversion of pyruvate to lactate. NAD(P)H fluorescence lifetimes depend on the bound or unbound state of the metabolite, which also relates to metabolic transitions between oxidative phosphorylation and glycolysis. To determine if fundamental metabolic profiles differ for cells that are sensitive to tamoxifen compared to those that are resistant, large populations of MCF-7 breast cancer cells were screened and fluorescence lifetimes were quantified. Additionally, metabolic differences associated with tamoxifen sensitivity were measured with a Seahorse HS mini metabolic analyzer (Agilent Technologies Inc. Santa Clara, CA) and confocal imaging. Results show that tamoxifen-resistant breast cancer cells have increased utilization of glycolysis for energy production compared to tamoxifen-sensitive breast cancer cells. This work is impacting because it establishes an early step toward developing a reliable screening technology in which large cell censuses can be differentiated for drug sensitivity in a label-free fashion.

Synchrotron circular dichroism (CD) is already a valuable technique for studies of protein folding, conformational changes and enzyme mechanisms, as well as secondary structure determination. Exciting new potential applications exist in protein folding, protein complex formation for Proteomics, and ligand/drug screening for Functional Genomics. With the 3 GeV synchrotron of Diamond Light Source we can collimate a very small size light beam (about 2 mm (H) × 1 mm (V)) with high photon flux (estimated 8 × 10¹³ (ph/s/0.1%bw) at 6 eV and 300 mA). The small beam size will enable the measurement of smaller sample volumes that previously has not been possible.

X-ray absorption fine structure (XAFS) spectroscopy has been widely used for decades in a wide range of scientific fields, including physics, chemistry, biology, materials, environmental sciences, and so on. In this chapter, we introduce the XAFS principles, including its basic theory, data analysis and experiment, from the view point of practical use. To show its strength as a local structure probe, applications of XAFS in various functional materials are introduced, covering nanoparticles and catalysts, magnetic semiconductors, thin film materials, complex compounds, in situ probing of the nucleation and growth processes of nanomaterials, as well as operando study of catalysts under working conditions.

In addition, we also briefly introduce some relatively new XAFS-related techniques, such as time-resolved and space-resolved XAFS techniques.

We discuss recent high-resolution angle-resolved photoemission (ARPES) and time-resolved ARPES experiments on selected surfaces which illustrate the formation of broken-symmetry ground states of very different nature: i) a Mott insulator in the layered dichalcogenide 1T-TaSe₂, and ii) a spin-orbit split state in the non-magnetic surface alloys BiAg₂ and PbAg₂.