An Introduction to Chirality at the Nanoscale

Vibrational optical activity

“…They have been extensively investigated and applied for many years in organic, inorganic and biochemistry [10][11][12] and, more recently, supramolecular chemistry and chiral nanoscience [13][14][15], with concomitant advances in computational methods [16][17][18][19]. It had long been appreciated that extending natural optical activity into the vibrational spectrum could provide more detailed and reliable stereochemical information because a vibrational spectrum contains many more bands sensitive to the details of the molecular structure (3N À 6 fundamentals, where N is the number of atoms) [2].…”

In pursuit of photo-induced magnetic and chiral microscopy

“…Alternatively, ad-hoc probe-tips for PiMFM or PiCFM can be fabricated separately and then "picked-up" and attached to the cantilever. Lanthanides and DNA have the capability to interact and contribute to optical magnetism and chirality [2,5,6,[59][60][61][62][63][64][65], therefore nanostructures incorporating these materials can serve as ideal probe-tips for optical magnetism or chirality detection purposes. Following this approach, a challenge is in firmly attaching such particles to the ideal position on the cantilever in a stable way.…”

“…Among the elusive material properties, we are particularly interested in photo-induced magnetism and chirality [1,2], due to their promising and fascinating implications, to name just a few: nanoscale magnetic imaging, magnetic tweezers and force microscopy, chirality detection, chiral force microscopy, magnetic spectroscopy, and spintronics, which have applications in material science, chemistry, and biology. However, both optical magnetism and chirality, which are related to the material's magnetic properties at optical frequencies, are typically weak and difficult to detect by conventional microscopy techniques that are typically based on the electric dipole response of the sample [2][3][4][5][6]. Moreover, the attempted nanoscale detection of such magnetic and chiral properties by conventional optical microscopy is especially difficult due to the diffraction limit.…”

Exciting a chiral dipole moment in an achiral nanostructure

“…Such a σ-dipole consists of parallel electric and magnetic dipole moments of equal amplitudes and a relative phase of ±π/2, leading to a well-defined helicity of ±1 in the far field [10,11]. Furthermore, the σ-dipole is conceptually similar to the coupled dipole moments observed for the fundamental mode of a chiral nanostructure [12][13][14][15]. There, the occurence of a σ-dipole component is directly linked to the chiral geometry of the system.…”