We report that non-contact optical temperature sensing can be achieved with the use of heavily Nd³⁺ doped NaYF₄ nanoparticles. The temperature evaluation can be realized either by monitoring the absolute luminescence intensity or by measuring the intensity ratio of the two Stark components of the ⁴F_3/2 multiplet in the Nd³⁺ ions.

A new type of near infrared absorbing near infrared emitting (NANE) luminescent nanothermometer is presented, whose physical background relies on efficient and temperature dependent Nd³⁺ to Yb³⁺ energy transfer under 808 nm photo-excitation.

A new type of luminescent thermometer based on highly temperature dependent d–d Cr ³⁺ transitions related to barely temperature dependent f–f Nd ³⁺ transitions for bio-application is reported for the first time, showing exceptionally high sensitivity.

Recent theoretical and experimental studies have indicated the existence of a new stable phase of carbon with mixed sp² and sp³ hybridized bonds—diaphite. Such a two-layered structure with sp²/sp³ bonds may be observed after the photostimulation of highly oriented pyrolytic graphene with femtosecond laser pulses. This hidden multistability of graphene may be used to create a semiconducting phase immersed in the semimetallic continuum, resulting in bandgap opening. We demonstrate that bandgap opening and light emission from graphene is possible using continuous-wave laser beams with wavelengths from the visible (405 nm) to the near-infrared range (975 nm). We demonstrate that without the application of cooling, the effective temperature of the emitting sample remains lower than 900 K, which is far below the value predicted by the theory of black-body radiation. Moreover, light emission from a graphene sample may be observed at temperatures as low as 10 K.

The highest relative sensitivity of YAG:Cr ³⁺ ,Nd ³⁺ luminescent thermometers in physiological temperature range was 3.48% K ⁻¹ .