Why are other elements such as calcium, oxygen, sodium, magnesium, aluminum, silicon and molybdenum visible in the EDX spectrum of tapered optical fiber (SMF‐28) covered with palladium and copper by sputtering method? Do all these foreign elements like silicon belong to the optical fiber itself?
If the optical fibre consists of glass, silicon and oxygen should be main constituents.
What are Cu and Pd for? Coatings to reduce charging are usually very thin (some nm) so the signal of the underlying material should be seen (for EDS carbon coating is preferred to get rid of additional element lines).
If a fibre is irradiated by high energy electrons (>10 keV) a certain scattering will occur, maybe the electrons will excite the tape used for fixing the sample.
Dear Prof. Baunack,
Thank you so much for your reply. The aim of deposition of Pd and Cu on optical fiber (on tapered section) is to enhance the performance of fiber optic sensor for hydrogen sensing. As you mentioned, the thickness of the deposited layer is small and about 50 nm. Regarding radiation with energetic electrons, your prediction is also correct and according to the manual of the device, the device works with radiations of about 15 keV.
According to your guidance, it seems that the presence of Si, O, and C can be related to optical fiber elements, and the rest to the diffraction of rays or SEM sample holder.
Your support has been invaluable to me. Thank you so much.
The image you sent shows the EDX results of a sputtered tapered optical fiber with palladium (Pd) and copper (Cu). Here's a breakdown of the key features:
Elements present:
The spectrum clearly shows peaks for the following elements:
Silicon (Si)
Oxygen (O)
Calcium (Ca)
Magnesium (Mg)
Aluminum (Al)
Copper (Cu)
Palladium (Pd)
As expected, silicon and oxygen are the most abundant elements, indicating the presence of the silica glass fiber core.
The presence of calcium, magnesium, and aluminum likely originates from the glass composition or impurities introduced during the fabrication process.
Copper and palladium peaks confirm the successful deposition of these metals on the tapered fiber.
Peak intensities:
The intensity of the Pd and Cu peaks is relatively low compared to Si and O peaks. This suggests that the metal layer is thin compared to the fiber core.
The Cu peak appears slightly stronger than the Pd peak, indicating a potentially higher concentration of copper in the deposited layer.
Additional observations:
The presence of Mo and C might be due to the sputtering equipment or target material.
The broad humps around 2 keV and 8 keV could be due to background noise or overlapping peaks from other elements.
Overall, the EDX results confirm the successful deposition of Pd and Cu on the sputtered tapered optical fiber. The thickness of the metal layer appears to be thin, and the Cu concentration might be slightly higher than Pd.
Dear Prof. Korea,
Thank you so much for your nice response. Your detailed response helps me a lot. That was great.
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