Zeeman deceleration is used to produce a slow beam of 00133&_mathId=si2.gif&_user=111111111&_pii=S0022285216300133&_rdoc=1&_issn=00222852&md5=ff3ec443ddce5554be04cd8deae46831">00133-si2.gif"> in selective spin–rotation levels.
Rydberg spectra of triplet He2 are recorded at high resolution with pulsed and cw radiation.
Extrapolation of Rydberg series is used to determine rotational intervals in 00133&_mathId=si7.gif&_user=111111111&_pii=S0022285216300133&_rdoc=1&_issn=00222852&md5=ffaac09afaa1300aa3f08da4774a532f">00133-si7.gif">.