Long Yu


Office: CLB 306
Office phone: 392-0562
E-mail: yulong@chem.ufl.edu

 

Education & Working:


2006-present

University of Florida, Ph.D. student,

Department of Chemistry

 

2005-2006

City University of Hong Kong, research assistant,
Department of Physics & Materials Science

    1. 2000-2004
    2. University of Science & Technology of China, B.S. in Physics,

Department of the Special Class for the Gifted Young


Research Interests:

 

In recent years, infrared multiple-photon dissociation (IRMPD) has emerged as a very convenient method to obtain spectroscopic information on gas-phase polyatomic molecules. We are particularly interested in peptide-based systems, as well as the products from collision-induced dissociation (CID). Peptides (e.g. Leu-enkephalin) are transferred to the gas phase by electrospray ionization (ESI) and trapped in a Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometer (see Figure). FT-ICR allows extended ion-trapping times at ultra-high vacuum, which enables long laser irradiation times while minimizing collisional relaxation. A frequency-tunable (wavelength range 2.3-4.6 micron, or 2200cm-1 to 4300 cm­-1, to cover the O-H, C-H, N-H stretches) optical parametric oscillator (OPO) laser is employed to photodissociate the mass-selected ions. The IR spectrum of an ion is then recorded by monitoring the photodissociation yield as a function of wavelength. In other words, photodissociation is only observed when the laser frequency is in resonance with a vibration of the molecule, whereas no dissociation is seen at other wavelengths.

 

In order to interpret these experimental results, theoretical spectra are required for reference. To achieve this, we first use (the commercially available) HyperChem program to perform a systematic approach to probe a large number of possible fragment structures by molecular dynamics. The best candidate structures are then further geometry-optimized by Gaussian and their IR spectra are calculated.

 

Many other types of molecules and complexes will be considered, including biomolecules linked to transition metals, etc.

 

 

FT-ICR mass spectrometer in the Powell Lab (4.7 T actively shielded Bruker APEX II). Linos OS 4000 cw OPO laser (Eyler group)