Hello!

I am working on optical sensors to detect few gases at high temperature. Gold nanoparticles prepared using citrate method (with intense absorbance peak at 530nm) are drop casted on quartz substrate, placed on the sample holder and mounted inside the quartz tube furnace. Light from the source (ocean optics HL series 2000) is allowed to collimate on the quartz substrate containing gold nanoparticles. The light detected by the photodetector is displayed on the spectrasuite software. When the furnace was heated to 300C or above the optical absorbance peak (at 530nm) deforms itself to a broad band.

1)what is the cause of deformation in the absorption peak?

2) Do gold nanoparticles tend to agglomerate at high temperature?

3) Is there any possible methods to achieve a smooth profile for optical absorption?

kindly help me in this regard. Thank you.