Table 3.
Side by side comparison of QEPAS sensor based on different QTFs for H2O detection. Overtone: overtone enhancement; sing-tube: single-tube on-beam configuration; f: QTF resonance frequency; λ: laser wavelength; P: laser power; α: absorption line intensity; D: detection limit; Ref: reference.
| Resonant Enhancement | f0 (kHz) | λ (nm) | P (mW) | α (cm/mol) | D (ppm) | Ref |
|---|---|---|---|---|---|---|
| Overtone + Single-tube | 25.4 | 7713 | 108 | 1.70 × 10−22 | 4.59 | [28] |
| Overtone + Single-tube | 17.7 | 1370 | 23 | 8.06 × 10−22 | 4.3 | [41] |
| On-beam configuration | 30.7 | 1395 | 30 | 1.17 × 10−20 | 4.3 | [40] |
| On-beam configuration | 32.7 | 1395 | \ | \ | 5.73 | [39] |
| Off-beam configuration | 32.7 | 1396 | 8 | 1.17 × 10−20 | 9.27 | [42] |
| None | 28 | 1392 | 5 | 3.07 × 10−21 | 6.3 | This work |