Quantum Light-Enhanced Two-Photon Imaging of Breast Cancer Cells.

Correct biological interpretation from cell imaging can be achieved only if the observed phenomena proceed with negligible perturbation from the imaging system. Herein, we demonstrate microscopic images of breast cancer cells created by the fluorescence selectively excited in the process of entangled two-photon absorption in a scanning microscope at an excitation intensity orders of magnitude lower than that used for classical two-photon microscopy. Quantum enhanced entangled two-photon microscopy has shown cell imaging capabilities at an unprecedented low excitation intensity of ∼3.

Origin of the "odd" behavior in the ultraviolet photochemistry of ozone.

The origin of the even-odd rotational state population alternation in the O(Δ) fragments resulting from the ultraviolet (UV) photodissociation of O, a phenomenon first observed over 30 years ago, has been elucidated using full quantum theory. The calculated O(Δ) rotational state distribution following the 266-nm photolysis of 60 K ozone shows a strong even-odd propensity, in excellent agreement with the new experimental rotational state distribution measured under the same conditions. Theory indicates that the even rotational states are significantly more populated than the adjacent odd rotational states because of a preference for the formation of the A' Λ-doublet, which can only occupy even rotational states due to the exchange symmetry of the two bosonic O nuclei, and thus not as a result of parity-selective curve crossing as previously proposed.

Evidence for lambda doublet propensity in the UV photodissociation of ozone.

The photodissociation of O at 266 nm has been studied using velocity mapped ion imaging. We report temperature-dependent vector correlations for the O(aΔ, v = 0, j = 18-20) fragments at molecular beam temperatures of 70 K, 115 K, and 170 K. Both the fragment spatial anisotropy and the v-j correlations are found to be increasingly depolarized with increasing beam temperature.

Nascent O ( Δ, = 0, 1) rotational distributions from the photodissociation of jet-cooled O in the Hartley band.

We report rotational distributions for the O ( Δ) fragment from the photodissociation of jet-cooled O at 248, 266, and 282 nm. The rotational distributions show a population alternation that favors the even states, as previously reported for a 300 K sample by Valentini [J. Chem.

Charge-tunable quantum plasmons in colloidal semiconductor nanocrystals.

Nanomaterials exhibiting plasmonic optical responses are impacting sensing, information processing, catalysis, solar, and photonics technologies. Recent advances have expanded the portfolio of plasmonic nanostructures into doped semiconductor nanocrystals, which allow dynamic manipulation of carrier densities. Once interpreted as intraband single-electron transitions, the infrared absorption of doped semiconductor nanocrystals is now commonly attributed to localized surface plasmon resonances and analyzed using the classical Drude model to determine carrier densities.

Controlling carrier densities in photochemically reduced colloidal ZnO nanocrystals: size dependence and role of the hole quencher.

Photodoped colloidal ZnO nanocrystals are model systems for understanding the generation and physical or chemical properties of excess delocalized charge carriers in semiconductor nanocrystals. Typically, ZnO photodoping is achieved photochemically using ethanol (EtOH) as a sacrificial reductant. Curiously, different studies have reported over an order of magnitude spread in the maximum number of conduction-band electrons that can be accumulated by photochemical oxidation of EtOH.

Size-dependent trap-assisted Auger recombination in semiconductor nanocrystals.

The acceleration of Auger-type multicarrier recombination in semiconductor nanocrystals impedes the development of many quantum-dot photonics, solar-cell, lighting, and lasing technologies. To date, only multiexciton and charged-exciton Auger recombination channels are known to show strong size dependence in nanocrystals. Here, we report the first observation of strongly accelerated "trap-assisted" Auger recombination rates in semiconductor nanocrystals.