This week's element is thulium, a lanthanide that has the symbol, Tm, and the atomic number, 69. It is very rare, being only slightly more common on Earth than promethium. Like the other lanthanides, ...

Thulium fiber lasers, operating at a wavelength of 2 μm, are valued for applications in medicine, materials processing, and defense. Their longer wavelength makes stray light less damaging compared to ...

Named after a mysterious place, thulium — one of the rarest rare earths — has some exotic chemistry in store for us, says Polly Arnold. Thulium — isolated by a Swedish chemist like so many of the ...