Frequency measurement of the 6S<sub>1/2 </sub>→5D<sub>5/2</sub> electric quadrupole transition of Cesium

<jats:p>&lt;p dir="ltr"&gt;We report a spectroscopy study on the 6S&lt;sub&gt;1/2 &lt;/sub&gt;→5D&lt;sub&gt;5/2&lt;/sub&gt; electric quadrupole transition of cesium at 685 nm using laser-induced heating loss of single atoms in optical tweezers and laser-induced fluorescence with cold atoms in a magneto-optical trap (MOT). Refer to a nearby molecular iodine transition, the frequency difference of the five hyperfine transitions, 6S&lt;sub&gt;1/2&lt;/sub&gt;, F=4&lt;sub&gt; &lt;/sub&gt;→5D&lt;sub&gt;5/2&lt;/sub&gt;, F'=6-2, are determined to ≲ 0.4 MHz uncertainty while the hyperfine spacings of the 5D&lt;sub&gt;5/2&lt;/sub&gt;, F'=6-2 states are determined to ≲ 0.1 MHz uncertainty. The absolute frequencies of the five hyperfine transitions are determined but are limited by the accuracy of iodine reference. Hyperfine coupling constants of the 5D&lt;sub&gt;5/2&lt;/sub&gt; state are determined to be A=-21.129(4) MHz and B=-0.28(6) MHz. Our work provides useful information for the relevant experiments that utilize this electric quadrupole transition.&lt;/p&gt;</jats:p>