Attention:The NSF Public Access Repository (PAR) system and access will be unavailable from 5:00 PM ET until 8:00 PM ET on Friday, September 11 due to maintenance. We apologize for the inconvenience.


Search for: All records

Creators/Authors contains: "Haldar, Neal"

Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher. Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?

Some links on this page may take you to non-federal websites. Their policies may differ from this site.

  1. The dynamics of photo-excited 4-bromophenolate anions in aqueous solution are investigated using femtosecond extreme ultraviolet (XUV) time-resolved photoelectron spectroscopy (TRPES) in a liquid flat jet. Excitation to the first singlet... 
    more » « less
    Free, publicly-accessible full text available May 14, 2027
  2. A setup for extreme-ultraviolet (XUV) time-resolved photoelectron spectroscopy of liquids is described based on a gas-dynamic flat jet formed by a microfluidic chip device. In comparison to a cylindrical jet that has a typical diameter of 10–30 µm, the larger surface area of the flat jet with a width of ∼300 µm allows for full overlap of the target with the pump and probe light beams. This results in an enhancement of photoelectrons emitted from the liquid while simultaneously allowing smaller sample consumption compared with other flat jet techniques utilizing liquid collisions or converging slits. Femtosecond pulses of XUV light at a photon energy of 21.7 eV are prepared by high harmonic generation and a multilayer mirror that selects a single harmonic; the He gas used to form the gas-dynamic flat jet is transparent at this energy. Compared to a cylindrical jet, the photoelectron signal from the liquid is enhanced relative to that from the surrounding vapor jacket. Pump–probe spectra for aqueous thymine show notably higher signals for the flat vs cylindrical jet. Moreover, the time-dependent space-charge shift in UV pump/XUV probe experiments is smaller for the gas-dynamic flat jet than for a cylindrical jet with the same flow rate, an effect that is accentuated at higher He backing pressures that yield a thinner jet. This reflects reduced multiphoton ionization of the solute by the UV pump pulse, the primary cause of the space charge shift, as the jet becomes thinner and reaches the thickness of a few tens of nm. 
    more » « less
  3. Extreme ultraviolet (XUV) time-resolved photoelectron spectroscopy is performed for a phenolate aqueous solution in liquid flat jets. Electron detachment dynamics upon excitation to S1and S2states are studied. 
    more » « less
    Free, publicly-accessible full text available March 25, 2027
  4. Ultrafast UV photophysics of adenine and its derivatives are interrogated by XUV-TRPES with a gas-dynamic flat liquid jet. 
    more » « less
  5. The UV-induced photo-relaxation dynamics of 5-bromouracil and 5-bromo-2′-deoxyuridine in aqueous solution were investigated using femtosecond time-resolved photoelectron spectroscopy with an extreme ultraviolet probe in a flat liquid jet. 
    more » « less