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Published on: December 27, 2018
Singlet molecular oxygen by direct excitation
Steffen Jockusch1, Nicholas J Turro, Elizabeth K Thompson
1Department of Chemistry, Columbia University, New York, NY 10027, USA.
Summary
Powerful YAG lasers enable direct excitation and detection of singlet oxygen at cryogenic temperatures. This research introduces a new method for mapping oxygen concentration and pressure, crucial for high-altitude aircraft design.
Area of Science:
- Physical Chemistry
- Spectroscopy
- Cryogenics
Background:
- Singlet molecular oxygen (O2) is a highly reactive species with significant implications in various chemical and biological processes.
- Direct excitation and detection of singlet oxygen at cryogenic temperatures present unique challenges due to its short lifetime and low concentrations.
Purpose of the Study:
- To investigate the direct excitation and luminescence detection of singlet molecular oxygen in the condensed phase at 77 K.
- To explore the potential application of this technique for quantitative, non-intrusive mapping of oxygen concentration and pressure.
Main Methods:
- Utilizing powerful YAG lasers for direct excitation at 1064 nm.
- Employing sensitive near-infrared (NIR) photomultipliers for detecting singlet oxygen luminescence at 1270 nm.
- Applying time-resolved luminescence spectroscopy and luminescence lifetime measurements.
Main Results:
- Successful generation and detection of singlet molecular oxygen in the condensed phase at 77 K without sensitizers.
- Observation of various luminescing species, including single molecule states ((1)Delta(g) and (1)Sigma(g)(+)) and the [(1)Delta(g)](2) simultaneous transition.
- Demonstration of luminescence intensity correlating with oxygen concentration.
Conclusions:
- Direct laser excitation and NIR detection provide a viable method for studying singlet oxygen at cryogenic temperatures.
- The developed technique offers a novel approach for quantitative, non-intrusive 2-D mapping of oxygen concentration and pressure.
- This method has potential applications in fields requiring precise oxygen monitoring at low temperatures, such as high-altitude aircraft design.
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