Resonant Enhancement of Two-Photon Absorption in Sodium Vapor

Abstract

tion of the form (21+ l)e' l/1° was necessary. No reason for this behavior was proffered and, subsequently, Ponomarev 9 has suggested that such a violent change in the initial I distribution, for nearby elements, seems unnatural. From the point of view of atomic dimensions, however, this is precisely the expectation, since the atomic diameters of Ti and Mn are 2.93 and 2.5 A, respectively. Thus, we would expect a truncation in I for the initial angular distribution in Mn which would be reflected later in the cascade by a diminished circular orbit population for Mn as compared to Ti.It may be possible to understand the reluctance of mesons to be captured into large angular momentum states in metals with small internuclear spacings on purely classical grounds. For a kaon to be captured into a state of I = 100H by an atom of radius 1 A requires the kaon to have a minimum kinetic energy of ~ 50 eV. Thus, if the kaon succeeds in escaping localization upon a single atom until it has a lower energy than this, capture into large-Z states would be quite unlikely. It should be pointed out that, even though there are many uncertainties in the calculations, several studies of the capture of slow negative mesons 6,10 have found that capture by a single atom occurs at energies somewhat in excess of this value.It would certainly be beneficial to extend mesonic atom x-ray intensity measurements to otherRecently there have appeared a number of papers demonstrating high-resolution two-photon spectroscopy in atomic vapors. 102 Especially interesting are the techniques which eliminate Doppler broadening by causing the atoms to absorb one photon from each of two beams of equal frequency propagating in opposite directions. 2 We have utilized a generalization of the opposing -targets and other incident projectiles (p, 2T, etc.). However, on the basis of the observations presented here, a study of the low-lying mesonic xray intensities in manganese or zinc in several of their crystalline forms should prove most interesting.beam technique to demonstrate resonant enhancement of the two-photon absorption cross section in sodium vapor. Our experiments were carried out using two single-mode, cw dye lasers operating at different frequencies. Large enhancements of more than 7 orders of magnitude and destructive-interference effects due to nearly resonant intermediate states are clearly demon -Resonant enhancement of over 7 orders of magnitude of the two-photon absorption cross section is observed in sodium vapor. Two cw dye-laser beams of different frequencies and propagating in opposite directions are utilized to generate high-resolution spectra which allow the enhancement as well as destructive-interference effects of nearly resonant intermediate states to be clearly demonstrated.128

Investigation of the fine structure in the2D sequence of sodium using level-crossing spectroscopy

“…The FS splittings in the n2D sequence of sodium are small, and because of this only the n = 3-6 members had until recently been measured by interferometry (Meissner and Luft 1937). With the introduction of the two-photon spectroscopy method, the 4'D state was extensively studied (Pritchard et a1 1974, Hansch et a / 1974, Bjorkholm and Liao 1974, Biraben et a1 1974. With similar techniques Levenson and Salour (1974) extended the measurements to the 52D state.…”

United Time-Frequency Spectroscopy for Dynamics and Global Structure

“…The two-photon transition rate was resonantly enhanced via available intermediate states using either two different excitation laser frequencies (13) or high-velocity atomic beams (14). High-resolution two-photon spectroscopy using picosecond pulsed light, hence without any appreciable intermediate-state interaction or absolute frequency reference, has been previously demonstrated (15,16).…”

“…However, their work suggests that versatile programmable molecular systems capable of algorithmic assembly into an infinite variety of 2D or three-dimensional (3D) supra-architectures with increasing pattern complexity, shape, molecular diversity, and size could potentially be generated with nucleic acids (10). Although more chemically labile than DNA, natural RNAs offer a richer treasure trove of rigid structural motifs (11)(12)(13)(14) that can be potential modules for supramolecular engineering (15)(16)(17)(18)(19)(20). RNA tectonics (15) refers to the modular character of RNA, which can be decomposed and reassembled to create new RNA nanoscopic architectures.…”

Frequency comb assisted two-photon vibrational spectroscopy

“…One of the light sources is the mid-infrared CW-OPO, which emits in the spectral region of the strong fundamental CH stretching vibrations. Tuning the exciting wavelengths near strong resonant transitions enhances the two-photon transition strength [30]. The second light source is an external cavity diode laser emitting in the nearinfrared region, where we can take advantage of highly developed cavity-enhanced detection methods to increase the sensitivity.…”