Difference-frequency laser

In dimers composed of equal molecules the dimer components can replace each other through tunneling. This effect has been discovered by Dyke et al. [1972] as interconversion splitting of rotational levels of (HF)2 in molecular beam electric resonance spectra. This dimer has been studied in many papers by microwave and far infrared tunable difference-frequency laser spectroscopy (see review papers by Truhlar [1990] and by Quack and Suhm [1991]). The dimer consists of two inequivalent HE molecules, the H atom of one of them participating in the hydrogen bond between the fluorine atoms (fig. 60). PES is a function of six variables indicated in this figure. 

Vibration-rotation spectra of OH and OD measured 807 using a difference frequency laser... 

In the columns identifying the experimental method, MW stands for any method studying the pure rotational spectrum of a molecule except for rotational Raman spectroscopy marked by the rot. Raman entry. FUR stands for Fourier transform infhired spectroscopy, IR laser for any infiured laser system (diode laser, difference frequency laser or other). LIF indicates laser induced fluorescence usually in the visible or ultraviolet region of the spectrum, joint marks a few selected cases where spectroscopic and diffraction data were used to determine the molecular structure. A method enclosed in parentheses means that the structure has been derived from data that were collected by this method in earlier publications. The type of structure determined is shown by the symbols identifying the various methods discussed in section II. V/ refers to determinations using the Kraitchman/Chutjian expressions or least squares methods fitting only isotopic differences of principal or planar moments (with or without first... 

The traditional method of noise subtraction has been revived and used very effectively for ion spectroscopy.°9 The laser beam is split into two parts, one for spectroscopy and the other for reference and detected by two matched infrared detectors. The signals from the two infrared detectors are elctronically combined with opposite phase to subtract noise. This method is particularly effective for a color center laser and a difference frequency laser system where the... 

A.S. Rine High-resolution methane U3-band spectra using a stabilized tunable difference-frequency laser system. J. Opt. Soc. Am. 66, 97 (1976) ... 

S. Stry, P. Hering, M. Mtirtz Portable difference-frequency laser-based cavity leak-out spectrometer for trace gas analysis. Appl. Phys. B75, 297 (2002)... 

Difference frequency lasers mix two beams of radiation, usually in the visible, at frequencies and V2 to generate infrared radiation at the frequency... 

I 2 1 the wavelength in microns of the difference frequency laser radiation generated by mixing beams with wavelengths 551 nm and 438 nm. 

M. Seiter, M.W. Sigrist Compact gas sensor using a pulsed difference-frequency laser spectrometer. Opt. Lett. 24, 110 (1999)... 

Amano T, Tanaka K (1985) Difference frequency laser spectroscopy of the i/j band of HOCO. J Chem Phys 82 1045-1046... 

To detect NH in the electronic ground state, the infrared absorption was applied in particular in solid matrices [21, 69] but also in the gas phase using a color center laser [70] and different frequency laser systems [71]. On the other hand, also the IR emission of NH(X v) was investigated experimentally and theoretically [72]. IR emission of the vibrational states of the X electronic state were also observed with Fourier transform emission spectroscopy [73] with low [74] and high resolution [75]. 

Difference-frequency laser (cw) (see Section 20.4.2.1 for the generation of difference frequency) By using various nonlinear crystals, this laser can cover almost the entire mid-infrared region (the lower limit is about 550 cm ). Since the width of this laser line is very narrow, this laser is important for performing high-resolution time-resolved measurements in the gaseous state. 

Figure 7 Spectrum of a gas mixture containing methane, methanol, ethanol, isopentane, benzene and toluene, all at ppm concentrations, buffered to 960 mbar total pressure with synthetic air (80% N2, 20% O2). The measured spectrum (+) was taken photoacous-tically with a difference frequency laser spectrometer based on an optical parametric oscillator (OPO) with a line width of 0.2 cm- Excellent agreement is obtained with the superimposed fitted spectrum (-) using the HITRAN database for methane and the pre-...

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