Related papers: Precise fine-structure and hyperfine-structure mea…
The frequency comb created by a femtosecond mode-locked laser and a microstructured fiber is used to phase coherently measure the frequencies of both the Hg^+ and Ca optical standards with respect to the SI second as realized at NIST. We…
We report absolute frequency, isotope shift, radiative lifetime and hyperfine structure measurements of the $^1P_1 \leftarrow{} ^{1}S_0$ (213.8 nm) transition in Zn I using a cryogenic buffer gas beam. Laser-induced fluorescence is…
The pursuit of ever more precise measures of time and frequency is likely to lead to the eventual redefinition of the second in terms of an optical atomic transition. To ensure continuity with the current definition, based on a microwave…
We report a precise measurement of the hyperfine interval in the ${2P}_{1/2}$ state of $^{7}$Li. The transition from the ground state ($D_1$ line) is accessed using a diode laser and the technique of saturated-absorption spectroscopy in hot…
We investigate 13 hyperfine structures of transition lines of 127I2 near 554 nm, namely, the R(50) 22-0, P(46) 22-0, P(121) 24-0, P(69) 25-1, R(146) 25-0, R(147) 28-1, P(160) 26-0, P(102) 26-1, R(96) 23-0, R(49) 22-0, P(45) 22-0, P(92)…
We measured the transition frequencies of the hyperfine components in the four lines (P(34) 39-0, R(36) 39-0, P(33) 39-0, and R(35) 39-0) of the B-X transitions of molecular iodine at 520.2 nm. The 520.2 nm laser was generated by…
We report absolute frequency measurements of the molecular iodine P(46) 5-4 $a_{1}$, $a_{10}$, and $a_{15}$ hyperfine transitions at 647 nm with a fiber-based frequency comb. The light source is based on a Littrow-type external-cavity diode…
Over five years we have compared the hyperfine frequencies of 133Cs and 87Rb atoms in their electronic ground state using several laser cooled 133Cs and 87Rb atomic fountains with an accuracy of ~10^{-15}. These measurements set a stringent…
In 2003 we have measured the absolute frequency of the $(1S, F=1, m_F=\pm 1) \leftrightarrow (2S, F'=1, m_F'=\pm 1)$ two-photon transition in atomic hydrogen. We observed a variation of $(-29\pm 57)$ Hz over a 44 months interval separating…
We developed a novel technique for frequency measurement and synthesis, based on the operation of a femtosecond comb generator as transfer oscillator. The technique can be used to measure frequency ratios of any optical signals throughout…
A spectrometer for ultra high-resolution spectroscopy of molecular iodine at wave length 501.7 nm, near the dissociation limit is described. Line shapes about 30 kHz wide (HWHM) were obtained using saturation spectroscopy in a pumped cell.…
We report on an absolute frequency measurement of the ${\rm Lu}^{+}\,(^{3}\rm D_1)$ standard frequency which is defined as the hyperfine-average of $^{1}\rm S_0$ to $^{3}\rm D_1$ optical clock transitions in $^{176}{\rm Lu}^{+}$. The…
We report the first absolute frequency measurements for the $5s5p^{3}$P$_{0}\to5s6d^{3}$D$_{1}$ transition at 394 nm for all the stable strontium isotopes by utilizing repumping induced spectroscopy in a magneto-optical trap. Absolute…
New set of wavenumber values for electronic-vibro-rotational (rovibronic) transitions in limited part of the emission spectrum of the $D_2$ molecule ($545 \div 627$ nm) have been measured with a precision $0.007 \div 0.1$ cm$^{-1}$…
We report observation of the $\rm 5S_{1/2} \rightarrow 5D_{5/2}$ two-photon transition in Rb vapor at 778 nm, using an external cavity diode laser system and a heated vapor cell. The spectra in the two isotopes show well-resolved hyperfine…
The absolute frequency of the 1S0-3P0 clock transition of 87Sr has been measured to be 429 228 004 229 873.65 (37) Hz using lattice-confined atoms, where the fractional uncertainty of 8.6x10-16 represents one of the most accurate…
We report absolute optical frequencies of electronic transitions from the $X\, ^2\Pi_{3/2},v''=0,J''=3/2$ rovibronic ground state to the 12 lowest levels of the $A\, ^2\Sigma^+,v'=0$ vibronic state in $^{16}$OH, as well as to the 16 lowest…
We report our measurements of the absolute transition frequencies of 5P_3/2,F = 3 to nS and nD Rydberg states of 87Rb with high principal quantum numbers in a wide range of values (n = 45-124). The measurements were performed using Rydberg…
High-resolution spectroscopy on the $A^2\Pi$ - $X^2\Sigma^+$ electronic system of $^{138}$Ba$^{19}$F is performed using a cold molecular beam produced by a buffer gas source. The hyperfine structure in both $X^2\Sigma^+$ ground and $A^2\Pi$…
We demonstrate a technique for locking the frequency of a tunable diode laser to a ring-cavity resonator. The resonator is stabilized to a diode laser which is in turn locked to an atomic transition, thus giving it absolute frequency…