Single Nanoparticle Mass Spectrometry as a High Temperature Kinetics Tool: Sublimation, Oxidation, and Emission Spectra of Hot Carbon Nanoparticles.

In single nanoparticle mass spectrometry, individual charged nanoparticles (NPs) are trapped in a quadrupole ion trap and detected optically, allowing their mass, charge, and optical properties to be monitored continuously. Previous experiments of this type probed NPs that were either fluorescent or large enough to detect by light scattering. Alternatively, small NPs can be heated to temperatures where thermally excited emission is strong enough to allow detection, and this approach should provide a new tool for measurements of sublimation and surface reaction kinetics of materials at high temperatures.

Photoluminescence of charged CdSe/ZnS quantum dots in the gas phase: effects of charge and heating on absorption and emission probabilities.

Gas phase spectral measurements for CdSe/ZnS core/shell nanocrystal quantum dots (QDs) before and after heating with both infrared (CO2) and visible lasers are reported. As-trapped QDs are spectrally similar to the same QDs in solution; however their photoluminescence (PL) intensities are very low, at least partly due to low absorption cross sections. After heating, the PL intensities brighten by factors ranging from ∼4 to 1800 depending on the QD size and pump laser wavelength.

Effects of translational and vibrational excitation on the reaction of HOD+ with C2H2 and C2D2: mode- and bond-specific effects in exoergic proton transfer.

Reactions of mode-selectively excited HOD(+) with C2H2 and C2D2 were studied over the center-of-mass collision energy (Ecol) range from 0.15 to 2.9 eV.

Optically detected, single nanoparticle mass spectrometer with pre-filtered electrospray nanoparticle source.

An instrument designed for non-destructive mass analysis of single trapped nanoparticles is described. The heart of the instrument is a 3D quadrupole (Paul) trap constructed to give optical access to the trap center along ten directions, allowing passage of lasers for particle heating and detection, particle injection, collection of scattered or fluorescent photons for particle detection and mass analysis, and collection of particles on TEM grids for analysis, as needed. Nanoparticles are injected using an electrospray ionization (ESI) source, and conditions are described for spraying and trapping polymer particles, bare metal particles, and ligand stabilized particles with masses ranging from 200 kDa to >3 GDa.

Single CdSe/ZnS nanocrystals in an ion trap: charge and mass determination and photophysics evolution with changing mass, charge, and temperature.

We report measurements of fluorescence intermittency (blinking) and spectral behavior for single semiconductor nanocrystal quantum dots (QDs) isolated in the gas phase and discuss the effects on fluorescence of the QD charge state and heating to the point of sublimation. Core-shell CdSe/ZnS QDs were trapped in a quadrupole ion trap and detected by laser-induced fluorescence. The mass (M) and charge (Q) were determined nondestructively, and both were followed continuously over the course of hours or days.

Structural elucidation of biological and toxicological complexes: investigation of monomeric and dimeric complexes of histidine with multiply charged transition metal (Zn and Cd) cations using IR action spectroscopy.

The gas-phase structures of singly and doubly charged complexes involving transition metal cations, Zn and Cd, bound to the amino acid histidine (His) as well as deprotonated His (His-H) are investigated using infrared multiple photon dissociation (IRMPD) spectroscopy utilizing light generated by a free electron laser. IRPMD spectra are measured for CdCl(+)(His), [Zn(His-H)](+), [Cd(His-H)](+), Zn(2+)(His)(2), and Cd(2+)(His)(2) in the 550-1800 cm(-1) range. These studies are complemented by quantum mechanical calculations of the predicted linear absorption spectra at the B3LYP/6-311+G(d,p) and B3LYP/Def2TZVP levels.