The combination of infrared laser spectroscopy with a molecular jet expansion provides a powerful technique to
investigate medium sized organic molecules and clusters. The coupling of quantum cascade lasers (QCLs) with two slit
jet infrared spectrometers, namely an off-axis cavity enhanced absorption (CEA) spectrometer and a rapid scan
spectrometer with an astigmatic multi-pass cell assembly, are described. Two types of QCLs, specifically a continuous
wave (cw) liquid nitrogen cooled distributed-feedback QCL at 5.7 μm, and a cw room temperature mode-hop-free
external cavity QCL centered at 6.1 μm, were employed as the light sources. A pair of 1 inch highly reflective cavity
ring-down mirrors (R = 99.98% at 5.2 μm) separated by 55 cm or a pair of 1.5 inch astigmatic mirrors separated by 20
cm, served as the optical cavities. To automate and to synchronize the timing of the CEA or rapid scan experiments with
a pulsed slit jet molecular expansion, two LabVIEW computer programs were developed. For the CEA experiments, one
of the cavity mirrors was mounted on a piezoelectric actuator with 1 inch clear aperture to maximize the effective mirror
size. The effects of mirror size and laser sweep rate were evaluated. A minimum detection sensitivity of 1.8×10-8 cm-1
was achieved. Jet-cooled molecules were generated using a homemade pulsed slit jet nozzle assembly. A jet-cooled
infrared spectrum of methyl lactate was recorded to demonstrate the performance of the CEA spectrometer. Preliminary
results obtained with the room temperature QCL coupled to the rapid scan spectrometer are also presented.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.