Question

Order these spectroscopy techniques by typical sample preparation complexity for solids (least to most). A. Raman with microscope
B. XPS
C. mid-IR transmission (KBr pellet)
Choose the correct answer from the options given below :

• A. A $<$ B $<$ C
• B. B $<$ C $<$ A
• C. B $<$ A $<$ C
• D. A $<$ C $<$ B

Hint:

Least prep: Raman → Moderate: XPS → Most: IR (KBr pellet).

Answer 1

The Correct Option is A

Concept: Different spectroscopic techniques require different levels of sample preparation, especially for solid samples. The complexity depends on whether the sample needs physical modification, vacuum conditions, or chemical treatment.

Step 1: Raman with microscope (A).
Raman spectroscopy with a microscope requires minimal sample preparation. Solid samples can often be analyzed directly without grinding or chemical treatment.
Thus, it has the least complexity.

Step 2: XPS (B).
X-ray Photoelectron Spectroscopy (XPS) requires:
• Ultra-high vacuum conditions
• Clean and flat sample surfaces Although no chemical mixing is needed, preparation and handling are more complex than Raman.

Step 3: mid-IR transmission (KBr pellet) (C).
This method requires:
• Grinding the sample
• Mixing with KBr powder
• Pressing into a pellet This makes it the most preparation-intensive method.

Step 4: Final ordering.
\[ A < B < C \] Final Conclusion:
Hence, the correct answer is option (1).