ترغب بنشر مسار تعليمي؟ اضغط هنا

Continuous probe of cold complex molecules with infrared frequency comb spectroscopy

53   0   0.0 ( 0 )
 نشر من قبل P. Bryan Changala
 تاريخ النشر 2016
  مجال البحث فيزياء
والبحث باللغة English
 تأليف Ben Spaun




اسأل ChatGPT حول البحث

Cavity-enhanced frequency comb spectroscopy for molecule detection in the mid-infrared powerfully combines high resolution, high sensitivity, and broad spectral coverage. However, this technique, and essentially all spectroscopic methods, is limited in application to relatively small, simple molecules. Here we integrate comb spectroscopy with continuous, cold samples of molecules produced via buffer gas cooling, thus enabling the study of significantly more complex molecules. We report simultaneous gains in resolution, sensitivity, and bandwidth and demonstrate this combined capability with the first rotationally resolved direct absorption spectra in the CH stretch region of several complex molecules. These include nitromethane (CH$_3$NO$_2$), a model system that presents challenging questions to the understanding of large amplitude vibrational motion, as well as several large organic molecules with fundamental spectroscopic and astrochemical relevance, including naphthalene (C$_{10}$H$_8$), adamantane (C$_{10}$H$_{16}$), and hexamethylenetetramine (C$_{6}$N$_4$H$_{12}$). This general spectroscopic tool has the potential to significantly impact the field of molecular spectroscopy, simultaneously improving efficiency, spectral resolution, and specificity by orders of magnitude. This realization could open up new molecular species and new kinetics for precise investigations, including the study of complex molecules, weakly bound clusters, and cold chemistry.



قيم البحث

اقرأ أيضاً

The discovery and characterization of exoplanets around nearby stars is driven by profound scientific questions about the uniqueness of Earth and our Solar System, and the conditions under which life could exist elsewhere in our Galaxy. Doppler spect roscopy, or the radial velocity (RV) technique, has been used extensively to identify hundreds of exoplanets, but with notable challenges in detecting terrestrial mass planets orbiting within habitable zones. We describe infrared RV spectroscopy at the 10 m Hobby-Eberly telescope that leverages a 30 GHz electro-optic laser frequency comb with nanophotonic supercontinuum to calibrate the Habitable Zone Planet Finder spectrograph. Demonstrated instrument precision <10 cm/s and stellar RVs approaching 1 m/s open the path to discovery and confirmation of habitable zone planets around M-dwarfs, the most ubiquitous type of stars in our Galaxy.
This paper reviews the recent results in high-resolution spectroscopy on cold molecules. Laser spectroscopy of cold molecules addresses issues of symmetry violation, like in the search for the electric dipole moment of the electron and the studies on energy differences in enantiomers of chiral species; tries to improve the precision to which fundamental physical constants are known and tests for their possible variation in time and space; tests quantum electrodynamics, and searches for a fifth force. Further, we briefly review the recent technological progresses in the fields of cold molecules and mid-infrared lasers, which are the tools that mainly set the limits for the resolution that is currently attainable in the measurements.
We perform heterodyne spectroscopy at 1.56 micron with a tunable laser and thermal radiation from the Sun. The laser tuning is calibrated with a frequency comb, providing a simple spectrometer with absolute frequency tracebility and resolving power of 2,000,000
Direct frequency comb spectroscopy of trapped ions is demonstated for the first time. It is shown that the 4s^2S_(1/2)-4p^2P_(3/2) transition in calcium ions can be excited directly with a frequency comb laser that is upconverted to 393 nm. Detection of the transition is performed using a shelving scheme to suppress background signal from non-resonant comb modes. The measured transition frequency of f=761 905 012.7(0.5) MHz presents an improvement in accuracy of more than two orders of magnitude.
We apply direct frequency-comb spectroscopy, in combination with precision cw spectroscopy, to measure the ${rm 4s4p} ^3P_1 to {rm 4s5s} ^3S_1$ transition frequency in cold calcium atoms. A 657 nm ultrastable cw laser was used to excite atoms on the narrow ($gamma sim 400$ Hz) ${rm 4s^2} ^1S_0 to {rm 4s4p} ^3P_1$ clock transition, and the direct output of the frequency comb was used to excite those atoms from the ${rm 4s4p} ^3P_1$ state to the ${rm 4s5s} ^3S_1$ state. The resonance of this second stage was detected by observing a decrease in population of the ground state as a result of atoms being optically pumped to the metastable ${rm 4s4p} ^3P_{0,2}$ states. The ${rm 4s4p} ^3P_1 to {rm 4s5s} ^3S_1$ transition frequency is measured to be $ u = 489 544 285 713(56)$ kHz; which is an improvement by almost four orders of magnitude over the previously measured value. In addition, we demonstrate spectroscopy on magnetically trapped atoms in the ${rm 4s4p} ^3P_2$ state.
التعليقات
جاري جلب التعليقات جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا