One of the most fundamental issues in water science is the characterization of H-bonding configuration formed on surfaces and H-atom transfer through hydrogen bonds. Ideally, attacking this problem requires the access to the internal degrees of freedom of water molecules, i.e. the directionality of OH bonds. In this talk, I will demonstrate the possibility of discerning the O-H directionality in real space through submolecular-resolution orbital imaging of interfacial water, using a cryogenic scanning tunneling microscope (STM) [1].

The ability to control and manipulate small objects is essential in studying many microscopic phenomena, from colloidal physics to molecular biology, and more recently, nanophotonics. Optical tweezers offer a unique non-contact approach to control the position and orientation of microscopic particles. In this lecture, I will introduce the development of optical tweezers with emphasis on the underlying physics of optical trapping, especially the interactions of light with plasmonic nanoparticles.